ci: update macos 10.15 to macos 12

Author: aminya

.github/workflows/ci.yml

@@ -30,7 +30,7 @@ jobs:
       matrix:
         os:
           - ubuntu-20.04
-          - macos-10.15
+          - macos-12
           - windows-2019
         compiler:
           # you can specify the version after `-` like "llvm-15.0.2".
@@ -63,7 +63,7 @@ jobs:
             enable_ipo: Off
             gcov_executable: "llvm-cov gcov"
 
-          - os: macos-10.15
+          - os: macos-12
             enable_ipo: Off
             enable_cppcheck: OFF
             enable_clang_tidy: OFF