ci: update Go to 1.21

Author: tklauser

.cirrus.yml

@@ -1,6 +1,6 @@
 env:
   CIRRUS_CLONE_DEPTH: 1
-  GO_VERSION: go1.20
+  GO_VERSION: go1.21.3
 
 freebsd_12_task:
   freebsd_instance:

.github/workflows/static-analysis.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Install Go
       uses: actions/setup-go@93397bea11091df50f3d7e59dc26a7711a8bcfbe
       with:
-        go-version: '1.19'
+        go-version: '1.21'
 
     - name: Check out code
       uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
   build-and-test:
     strategy:
       matrix:
-        go-version: ['1.18', '1.19', '1.20']
+        go-version: ['1.19', '1.20', '1.21']
         os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
 
@@ -26,11 +26,11 @@ jobs:
       uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
 
     - name: Check formatting
-      if: ${{ matrix.go-version == '1.20' && matrix.os == 'ubuntu-latest' }}
+      if: ${{ matrix.go-version == '1.21' && matrix.os == 'ubuntu-latest' }}
       run: diff -u <(echo -n) <(gofmt -d .)
 
     - name: Check Go modules
-      if: ${{ matrix.go-version == '1.20' && matrix.os == 'ubuntu-latest' }}
+      if: ${{ matrix.go-version == '1.21' && matrix.os == 'ubuntu-latest' }}
       run: |
         go mod tidy
         git diff --exit-code