Attempt to fix macOS CI

Author: slonopotamus

Diff for: .github/workflows/ci.yml

@@ -6,7 +6,7 @@ on:
   pull_request:
 jobs:
   rubocop:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -22,7 +22,7 @@ jobs:
       matrix:
         ruby: [ 'jruby-9.3', 'jruby-9.4', '2.6', '3.3' ]
         python: [ '3.6', '3.12' ]
-        platform: [ ubuntu-20.04, macos-latest, windows-2019 ]
+        platform: [ ubuntu-22.04, macos-12, windows-2019 ]
     runs-on: ${{ matrix.platform }}
     steps:
       - name: Checkout

Diff for: .github/workflows/release.yml

@@ -4,7 +4,7 @@ on:
     tags: [ '*' ]
 jobs:
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4
       - name: Set up Ruby