Bump golang version.

Bump golang version to v1.21.
Bump golang.org/x/net version to v0.17.0 in Velero and Restic.

Signed-off-by: Xun Jiang <jxun@vmware.com>

.github/workflows/crds-verify-kind.yaml

@@ -14,7 +14,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v4
         with:
-          go-version: '1.20'
+          go-version: '1.21'
         id: go
       # Look for a CLI that's made for this PR
       - name: Fetch built CLI

.github/workflows/e2e-test-kind.yaml

@@ -14,7 +14,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v4
         with:
-          go-version: '1.20'
+          go-version: '1.21'
         id: go
       # Look for a CLI that's made for this PR
       - name: Fetch built CLI
@@ -72,7 +72,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v4
         with:
-          go-version: '1.20'
+          go-version: '1.21'
         id: go
       - name: Check out the code
         uses: actions/checkout@v2

.github/workflows/pr-ci-check.yml

@@ -10,7 +10,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v4
         with:
-          go-version: '1.20'
+          go-version: '1.21'
         id: go
       - name: Check out the code
         uses: actions/checkout@v2

.github/workflows/push.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v4
       with:
-        go-version: '1.20'
+        go-version: '1.21'
       id: go
 
     - uses: actions/checkout@v3