fix: impl Send and Sync for formats

src/format/format/input.rs

@@ -7,6 +7,9 @@ pub struct Input {
 	ptr: *mut AVInputFormat,
 }
 
+unsafe impl Send for Input { }
+unsafe impl Sync for Input { }
+
 impl Input {
 	pub unsafe fn wrap(ptr: *mut AVInputFormat) -> Self {
 		Input { ptr }

src/format/format/output.rs

@@ -13,6 +13,9 @@ pub struct Output {
 	ptr: *mut AVOutputFormat,
 }
 
+unsafe impl Send for Output { }
+unsafe impl Sync for Output { }
+
 impl Output {
 	pub unsafe fn wrap(ptr: *mut AVOutputFormat) -> Self {
 		Output { ptr }