Bump Go 1.13.13

Includes security fixes to the `crypto/x509` and `net/http` packages.

https://github.com/golang/go/issues?q=milestone%3AGo1.13.13+label%3ACherryPickApproved

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

.github/workflows/release.yml

@@ -62,7 +62,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v1
         with:
-          go-version: '1.13.12'
+          go-version: '1.13.13'
 
       - name: Set env
         shell: bash