lp-snap-builder action v3 (#14638)

The system PATH on GHA runners needs to be updated in a special way:
https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions#adding-a-system-path

.github/actions/lp-snap-build/action.yml

@@ -56,3 +56,9 @@ runs:
         # Depends on Go being available which is the case in the GitHub Actions environment
         set -eux
         go install github.com/canonical/lxd-ci/lxd-snapcraft@latest
+
+        # Update system PATH to add ~/go/bin if needed
+        echo "${PATH}"
+        if ! echo "${PATH}" | grep -F go/bin; then
+          echo "$(go env GOPATH)/bin" >> "${GITHUB_PATH}"
+        fi

.github/workflows/tests.yml

@@ -684,6 +684,7 @@ jobs:
       - name: Trigger Launchpad snap build
         run: |
           set -eux
+          echo "${PATH}"
           localRev="$(git rev-parse HEAD)"
           cd ~/"${PACKAGE}-pkg-snap-lp"
           lxd-snapcraft -package "${PACKAGE}" -set-version "git-${localRev:0:7}" -set-source-commit "${localRev}"