Update ci.yml

Author: stephencelis

.github/workflows/ci.yml

@@ -14,8 +14,8 @@ jobs:
     strategy:
       matrix:
         xcode:
-          - 12.4
-          - 12.5
+          - '12.4'
+          - '12.5.1'
           - '13.0'
     steps:
       - uses: actions/checkout@v2
@@ -34,8 +34,8 @@ jobs:
     strategy:
       matrix:
         xcode:
-          - 12.4
-          - 12.5
+          - '12.4'
+          - '12.5.1'
           - '13.0'
     steps:
       - uses: actions/checkout@v2