Remove the --filename option for rec and session commands

Most of it can be done by using variable interpolation in a shell e.g.:

  asciinema rec "${HOSTNAME}-${USER}-$(date +%s)-$$.cast"

Cargo.lock

@@ -26,21 +26,6 @@ dependencies = [
  "memchr",
 ]
 
-[[package]]
-name = "android-tzdata"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e999941b234f3131b00bc13c22d06e8c5ff726d1b6318ac7eb276997bbb4fef0"
-
-[[package]]
-name = "android_system_properties"
-version = "0.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "819e7219dbd41043ac279b19830f2efc897156490d7fd6ea916720117ee66311"
-dependencies = [
- "libc",
-]
-
 [[package]]
 name = "anstream"
 version = "0.6.18"
@@ -104,13 +89,11 @@ dependencies = [
  "anyhow",
  "avt",
  "axum",
- "chrono",
  "clap",
  "clap_complete",
  "clap_mangen",
  "config",
  "futures-util",
- "hostname",
  "mime_guess",
  "nix 0.30.1",
  "reqwest",
@@ -361,20 +344,6 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
 
-[[package]]
-name = "chrono"
-version = "0.4.41"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c469d952047f47f91b68d1cba3f10d63c11d73e4636f24f08daf0278abf01c4d"
-dependencies = [
- "android-tzdata",
- "iana-time-zone",
- "js-sys",
- "num-traits",
- "wasm-bindgen",
- "windows-link",
-]
-
 [[package]]
 name = "clang-sys"
 version = "1.8.1"
@@ -888,17 +857,6 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
-[[package]]
-name = "hostname"
-version = "0.4.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a56f203cd1c76362b69e3863fd987520ac36cf70a8c92627449b2f64a8cf7d65"
-dependencies = [
- "cfg-if",
- "libc",
- "windows-link",
-]
-
 [[package]]
 name = "html5ever"
 version = "0.29.1"
@@ -1015,30 +973,6 @@ dependencies = [
  "tracing",
 ]
 
-[[package]]
-name = "iana-time-zone"
-version = "0.1.63"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b0c919e5debc312ad217002b8048a17b7d83f80703865bbfcfebb0458b0b27d8"
-dependencies = [
- "android_system_properties",
- "core-foundation-sys",
- "iana-time-zone-haiku",
- "js-sys",
- "log",
- "wasm-bindgen",
- "windows-core",
-]
-
-[[package]]
-name = "iana-time-zone-haiku"
-version = "0.1.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f31827a206f56af32e590ba56d5d2d085f558508192593743f16b2306495269f"
-dependencies = [
- "cc",
-]
-
 [[package]]
 name = "icu_collections"
 version = "1.5.0"
@@ -1460,15 +1394,6 @@ dependencies = [
  "winapi",
 ]
 
-[[package]]
-name = "num-traits"
-version = "0.2.19"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
-dependencies = [
- "autocfg",
-]
-
 [[package]]
 name = "numtoa"
 version = "0.1.0"
@@ -3016,41 +2941,6 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
 
-[[package]]
-name = "windows-core"
-version = "0.61.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4763c1de310c86d75a878046489e2e5ba02c649d185f21c67d4cf8a56d098980"
-dependencies = [
- "windows-implement",
- "windows-interface",
- "windows-link",
- "windows-result",
- "windows-strings 0.4.0",
-]
-
-[[package]]
-name = "windows-implement"
-version = "0.60.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a47fddd13af08290e67f4acabf4b459f647552718f683a7b415d290ac744a836"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
-[[package]]
-name = "windows-interface"
-version = "0.59.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bd9211b69f8dcdfa817bfd14bf1c97c9188afa36f4750130fcdf3f400eca9fa8"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
 [[package]]
 name = "windows-link"
 version = "0.1.1"
@@ -3064,7 +2954,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4286ad90ddb45071efd1a66dfa43eb02dd0dfbae1545ad6cc3c51cf34d7e8ba3"
 dependencies = [
  "windows-result",
- "windows-strings 0.3.1",
+ "windows-strings",
  "windows-targets 0.53.0",
 ]
 
@@ -3086,15 +2976,6 @@ dependencies = [
  "windows-link",
 ]
 
-[[package]]
-name = "windows-strings"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a2ba9642430ee452d5a7aa78d72907ebe8cfda358e8cb7918a2050581322f97"
-dependencies = [
- "windows-link",
-]
-
 [[package]]
 name = "windows-sys"
 version = "0.52.0"