update to go1.21.13

- https://github.com/golang/go/issues?q=milestone%3AGo1.21.13+label%3ACherryPickApproved
- full diff: https://github.com/golang/go/compare/go1.21.12...go1.21.13

go1.21.13 (released 2024-08-06) includes fixes to the go command, the
covdata command, and the bytes package. See the [Go 1.21.13 milestone](https://github.com/golang/go/issues?q=milestone%3AGo1.21.13+label%3ACherryPickApproved)
on our issue tracker for details.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
(cherry picked from commit 434d8b75e8)
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

.github/workflows/test.yml

@@ -65,7 +65,7 @@ jobs:
         name: Set up Go
         uses: actions/setup-go@v5
         with:
-          go-version: 1.21.12
+          go-version: 1.21.13
       -
         name: Test
         run: |