Set Actions Go version from go.mod (#389)

The `.palantir/go-version` file is no longer supported, so always build
with the latest patch release of the version specified in `go.mod.` This
mostly matches the behavior we're adopting internally, with the main
difference being that we'll never build with a newer major version of Go
than what is specified in our `go.mod` file. We can't rely on the
default behavior of the `setup-go` action because it always downloads
the exact version in `go.mod` when a patch version is specified.

Author: bluekeyes

.github/workflows/build.yml

@@ -24,7 +24,7 @@ jobs:
     - name: Set Go version
       id: go_version
       run: |
-        GO_VERSION=$(cat .palantir/go-version | sed 's/^go//' )
+        GO_VERSION=$(sed -E -n '/^go / s/^go ([0-9]+\.[0-9]+)(\.[0-9]+)?$/\1/p' < go.mod)
         echo "version=${GO_VERSION}" >> $GITHUB_OUTPUT
 
     - name: Set up Go

.github/workflows/codeql-analysis.yml

@@ -33,7 +33,7 @@ jobs:
     - name: Set Go version
       id: go_version
       run: |
-        GO_VERSION=$(cat .palantir/go-version | sed 's/^go//' )
+        GO_VERSION=$(sed -E -n '/^go / s/^go ([0-9]+\.[0-9]+)(\.[0-9]+)?$/\1/p' < go.mod)
         echo "version=${GO_VERSION}" >> $GITHUB_OUTPUT
 
     - name: Set up Go