package: allow modular java 8 projects

even if you compile with --release 8, javac will still emit a
module-info.class with it's version set to 53 (java 9) if you have a
module-info.java

.github/workflows/build.yml

@@ -29,7 +29,7 @@ jobs:
         path: |
           ~/.gradle/caches/
           ~/.gradle/wrapper/
-        key: package-2.0.8
+        key: package-2.0.9
     - name: prepare
       run: |
         pushd package
@@ -82,7 +82,7 @@ jobs:
         path: |
           ~/.gradle/caches/
           ~/.gradle/wrapper/
-        key: upload-2.0.8
+        key: upload-2.0.9
     - uses: actions/download-artifact@v2
       with:
         name: manifest_diff