Fix MPV library naming.

.github/workflows/main.yml

@@ -63,7 +63,7 @@ jobs:
         mv mpv include
         mkdir mpv
         mv include mpv
-        mv mpv-2.dll mpv/mpv.dll
+        mv libmpv-2.dll mpv/mpv.dll
         mv mpv.def libmpv.dll.a mpv/
         mv mpv build/
       shell: bash
@@ -108,7 +108,7 @@ jobs:
         mv mpv include
         mkdir mpv
         mv include mpv
-        mv mpv-2.dll mpv/mpv.dll
+        mv libmpv-2.dll mpv/mpv.dll
         mv mpv.def libmpv.dll.a mpv/
         mv mpv build/
       shell: bash