add OpenGL framework

.github/workflows/macos.yml

@@ -9,10 +9,6 @@ jobs:
         with:
           fetch-depth: 0
 
-      - uses: maxim-lobanov/setup-xcode@v1
-        with:
-          xcode-version: '12.0'
-
       - name: Install dependencies
         run: |
           brew install meson ninja libass

meson.build

@@ -264,7 +264,7 @@ if host_machine.system() == 'windows' and not get_option('directsound').disabled
 endif
 
 if host_machine.system() == 'darwin'
-    frameworks_dep = dependency('appleframeworks', modules : ['CoreText', 'CoreFoundation'])
+    frameworks_dep = dependency('appleframeworks', modules : ['CoreText', 'CoreFoundation', 'OpenGL'])
     deps += frameworks_dep
 endif