Add node_modules on master with up-to-date deps

GitHub Actions tutorials suggest that you should not commit Node.js crap
onto your master branch, but it's not like this action has a lot of
dependencies, and not being able to test "ilammy/msvc-dev-cmd@master" is
so annoying... Therefore, do

    npm install --only production

and commit the results.

node_modules/@actions/core/lib/file-command.d.ts

@@ -0,0 +1 @@
+export declare function issueCommand(command: string, message: any): void;