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

examples/metadata.rs

@@ -73,10 +73,14 @@ fn main() -> Result<(), ffmpeg::Error> {
                         println!("\tmax_rate: {}", audio.max_bit_rate());
                         println!("\tdelay: {}", audio.delay());
                         println!("\taudio.rate: {}", audio.rate());
-                        println!("\taudio.channels: {}", audio.channels());
                         println!("\taudio.format: {:?}", audio.format());
-                        println!("\taudio.frames: {}", audio.frames());
                         println!("\taudio.align: {}", audio.align());
+                        #[cfg(feature = "ffmpeg_5_1")]
+                        println!("\taudio.ch_layout: {:?}", audio.ch_layout());
+
+                        #[cfg(not(feature = "ffmpeg_5_1"))]
+                        println!("\taudio.channels: {}", audio.channels());
+                        #[cfg(not(feature = "ffmpeg_5_1"))]
                         println!("\taudio.channel_layout: {:?}", audio.channel_layout());
                     }
                 }