Merge pull request #202 from AkihiroSuda/macos-11-ci

CI: bump up macos-10.15 to macos-11

Author: jandubois

.github/workflows/test.yml

@@ -67,7 +67,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-10.15, ubuntu-20.04]
+        os: [macos-11, ubuntu-20.04]
     timeout-minutes: 20
     steps:
       - uses: actions/setup-go@v2
@@ -89,7 +89,7 @@ jobs:
 
   integration:
     name: Integration tests
-    runs-on: macos-10.15
+    runs-on: macos-11
     timeout-minutes: 40
     strategy:
       matrix: