.github: Bump minimum Go version to 1.21

Signed-off-by: Thomas Hipp <thomashipp@gmail.com>

.github/workflows/tests.yml

@@ -44,11 +44,11 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v5
         with:
-          go-version: 1.20.x
+          go-version: 1.21.x
 
       - name: Check compatible min Go version
         run: |
-          go mod tidy -go=1.20
+          go mod tidy -go=1.21
 
       - name: Install dependencies
         run: |
@@ -111,7 +111,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        go: ["1.20.x"]
+        go: ["1.21.x"]
         suite: ["cluster", "standalone"]
         backend: ["dir", "btrfs", "lvm", "zfs", "ceph", "random"]
         include:
@@ -329,7 +329,7 @@ jobs:
       fail-fast: false
       matrix:
         go:
-          - 1.20.x
+          - 1.21.x
         os:
           - ubuntu-latest
           - macos-latest
@@ -403,7 +403,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v5
         with:
-          go-version: 1.20.x
+          go-version: 1.21.x
 
       - name: Install dependencies
         run: |