chore: require newer golang version when running tests

This will hopefully address the "Test with Coverage: malformed module path
"crypto/ecdh": missing dot in first path element" issue.  The required
version is based on fact commit that introduced crypto/ecdh started it's
exsistence in the go1.20.

    go-sources $ git tag --contain d88d91e32e1440307369d50ba17ce622399a8bc1
    go1.20

Reference: golang/go@d88d91e
Signed-off-by: Sami Kerola <kerolasa@iki.fi>

.github/workflows/go.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Set up Go 1.x
       uses: actions/setup-go@v2
       with:
-        go-version: ^1.13
+        go-version: '>=1.20.0'
       id: go
 
     - name: Check out code into the Go module directory

.github/workflows/test.yaml

@@ -15,7 +15,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v1
         with:
-          go-version: '1.13'
+          go-version: '>=1.20.0'
 
       - name: Check out code
         uses: actions/checkout@v2