chore(deps): move x264 to master branch (#439)

Author: ReenigneArcher

.gitmodules

@@ -5,7 +5,7 @@
 [submodule "third-party/FFmpeg/x264"]
 	path = third-party/FFmpeg/x264
 	url = https://github.com/LizardByte-infrastructure/x264.git
-	branch = stable
+	branch = master
 [submodule "third-party/FFmpeg/x265_git"]
 	path = third-party/FFmpeg/x265_git
 	url = https://github.com/LizardByte-infrastructure/x265_git.git