tests/thirdparty: update golang/go tests to 1.20.1 (#378)

The Go third-party compatibility tests were pinned to the release
candidate version. This change uses the now official Go 1.20.1 release
tag.

.github/workflows/packages.yml

@@ -947,7 +947,7 @@ jobs:
         uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8 # v3.1.0
         with:
           repository: golang/go
-          ref: go1.20rc2
+          ref: go1.20.1
           path: go
           persist-credentials: false
       - name: Compile Go Toolchain
@@ -985,7 +985,7 @@ jobs:
         uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8 # v3.1.0
         with:
           repository: golang/go
-          ref: go1.20rc2
+          ref: go1.20.1
           path: go
           persist-credentials: false
       - name: Compile Go Toolchain