Support FFmpeg 7.0 (#48)

* sys: Run cargo fmt

* sys: Add new channel layout consts

* sys: Update build script for 7.0

- Add new FF_API flags
- Update version_check_info range
- Add ffmpeg_7_0 feature entry

* sys: Update non-exhaustive match statement

* Update enums

* Mark old APIs as removed with 7.0

* Make Audio frame work with 7.0

The .unwrap() in clone() is a bit wonky

* Add API for swr_alloc_set_opts2

* Use AVFrame::duration field in 7.0+

* Include 7.0 in CI runs

* Add fn ChanneLayoutIter::best

* Update examples for new API

* Add/update Context setter for ch layout

src/util/channel_layout/layout.rs

@@ -306,6 +306,11 @@ impl<'a> ChannelLayout<'a> {
     pub const _7POINT1POINT2: Scl = ChannelLayout(Cow::Owned(AV_CHANNEL_LAYOUT_7POINT1POINT2));
     pub const _7POINT1POINT4_BACK: Scl =
         ChannelLayout(Cow::Owned(AV_CHANNEL_LAYOUT_7POINT1POINT4_BACK));
+    #[cfg(feature = "ffmpeg_7_0")]
+    pub const _7POINT2POINT3: Scl = ChannelLayout(Cow::Owned(AV_CHANNEL_LAYOUT_7POINT2POINT3));
+    #[cfg(feature = "ffmpeg_7_0")]
+    pub const _9POINT1POINT4_BACK: Scl =
+        ChannelLayout(Cow::Owned(AV_CHANNEL_LAYOUT_9POINT1POINT4_BACK));
     pub const HEXADECAGONAL: Scl = ChannelLayout(Cow::Owned(AV_CHANNEL_LAYOUT_HEXADECAGONAL));
     pub const STEREO_DOWNMIX: Scl = ChannelLayout(Cow::Owned(AV_CHANNEL_LAYOUT_STEREO_DOWNMIX));
     pub const _22POINT2: Scl = ChannelLayout(Cow::Owned(AV_CHANNEL_LAYOUT_22POINT2));