ci: use go 1.21

Author: markus-wa

.github/workflows/ci.yml

@@ -4,10 +4,6 @@ name: CI
 
 jobs:
   ci:
-    strategy:
-      matrix:
-        go-version: [1.18.x]
-
     runs-on: ubuntu-latest
 
     env:
@@ -18,7 +14,7 @@ jobs:
     - name: Install Go
       uses: actions/setup-go@v2
       with:
-        go-version: ${{ matrix.go-version }}
+        go-version: 1.21.x
 
     - name: Install Reviewdog
       uses: reviewdog/action-setup@v1

.github/workflows/protobuf.yml

@@ -27,7 +27,7 @@ jobs:
         if: env.PROTOBUFS_CHANGED == 'true'
         uses: actions/setup-go@v2
         with:
-          go-version: 1.18.x
+          go-version: 1.21.x
 
       - name: Install Protobuf tools
         if: env.PROTOBUFS_CHANGED == 'true'