Release notes gen: Fix previous tag calculation

The latest version of gren (0.17.3) has a bug [0] which causes
it to include all issues rather than just than since the last
tag. This pins to 0.17.1 to avoid this bug.

This also limits the previous tag search to airshipctl semver tags,
that is those without a krm function prefix.

[0]: https://github.com/github-tools/github-release-notes/issues/279

Change-Id: Ib3524bef7a52da97a89f0bc408a1b2e1072e64b1
Signed-off-by: Sean Eagan <seaneagan1@gmail.com>

.github/workflows/release.yaml

@@ -98,7 +98,7 @@ jobs:
           fetch-depth: 0
       - name: Download release notes utility
         run: |
-          sudo npm install github-release-notes -g
+          sudo npm install github-release-notes@0.17.1 -g
       - name: Generate release notes
         run: |
           TAG_NAME=${TAG##*/}
@@ -107,6 +107,7 @@ jobs:
             --changelog-filename release-notes.md \
             --token "$GITHUB_TOKEN" \
             --tags "$TAG_NAME" \
+            --ignore-tags-with '^(?!v\d)' `# only consider semver tags without krm function prefix when finding previous tag` \
             --debug
           cat release-notes.md
         env: