fix: handle informational "No ..." messages from oasdiff v1.14.0

oasdiff v1.14.0 prints "No changes to report, but the specs are
different" when the diff is non-empty but no breaking/changelog entries
are found (e.g. all suppressed via --err-ignore). The entrypoint scripts
treated any non-empty output as actual changes, which caused the
::notice:: upgrade link to fire incorrectly and the wrong output string.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: reuvenharrison

breaking/entrypoint.sh

@@ -99,7 +99,7 @@ oasdiff breaking "$base" "$revision" $flags_with_githubactions
 delimiter=$(cat /proc/sys/kernel/random/uuid | tr -d '-')
 echo "breaking<<$delimiter" >>"$GITHUB_OUTPUT"
 
-if [ -n "$breaking_changes" ]; then
+if [ -n "$breaking_changes" ] && ! echo "$breaking_changes" | head -n 1 | grep -q "^No "; then
     write_output "$(echo "$breaking_changes" | head -n 1)" "$breaking_changes"
     # Emit upgrade notice pointing to the free review page
     urlencode() { printf '%s' "$1" | jq -sRr @uri; }

changelog/entrypoint.sh

@@ -97,7 +97,7 @@ else
     output=$(oasdiff changelog "$base" "$revision")
 fi
 
-if [ -n "$output" ]; then
+if [ -n "$output" ] && ! echo "$output" | head -n 1 | grep -q "^No "; then
     write_output "$output"
 else
     write_output "No changelog changes"