ci: Pin macOS to 10.15

macOS-latest now means macOS-11.

diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index e4fd3d70db99ea0c86092fd4a6f79bc1babc6d1c..7c0ed3a36100e85f5253299c4ef1d2a8ed725588 100644 (file)
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -70,17 +70,17 @@ jobs:
             compiler: clang
             version: "11"
 
-          - os: macOS-latest
+          - os: macOS-10.15
             compiler: xcode
             version: "10.3"
 
-          - os: macOS-latest
+          - os: macOS-10.15
             compiler: xcode
             version: "11.7"
 
-          - os: macOS-latest
+          - os: macOS-10.15
             compiler: xcode
-            version: "12.2"
+            version: "12.4"
     steps:
       - name: Install dependencies
         run: |