ci: make CI job fail when check-deps.sh script fails

Previously the check-deps.sh would write information about unexpected
dependencies to stderr, but return exit code 0, so the error would be ignored
by CI. Now it will return code 1 and cause CI to fail if unexpected
dependencies are detected.

contrib/devtools/check-deps.sh

@@ -194,7 +194,10 @@ cd "$BUILD_DIR/src"
 extract_symbols "$TEMP_DIR"
 if check_libraries "$TEMP_DIR"; then
     echo "Success! No unexpected dependencies were detected."
+    RET=0
 else
     echo >&2 "Error: Unexpected dependencies were detected. Check previous output."
+    RET=1
 fi
 rm -r "$TEMP_DIR"
+exit $RET