Add support for publishing a package that isn't at repo root

Author: adrw

README.md

@@ -20,3 +20,15 @@ you'll need to configure that workflow yourself. You can look to the
   * All other changes will increment the patch version.
 * Publish to npm using the configured token.
 * Push a tag for the new version to GitHub.
+
+### Additional Configuration
+
+* If your `package.json` is not in the repo's root directory, Set `PACKAGE_PATH` env variable if `package.json` is not in repo root directory
+  ```
+  - name: Publish
+      uses: mikeal/merge-release@master
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        NPM_AUTH_TOKEN: ${{ secrets.NPM_AUTH_TOKEN }}
+        PACKAGE_PATH: ./packages/my-package
+  ```

merge-release-run.js

@@ -12,7 +12,7 @@ const get = bent('json', process.env.NPM_REGISTRY_URL || 'https://registry.npmjs
 
 const event = JSON.parse(fs.readFileSync('/github/workflow/event.json').toString())
 
-let pkg = require(path.join(process.cwd(), 'package.json'))
+let pkg = require(path.join(process.env.PACKAGE_PATH || process.cwd(), 'package.json'))
 
 const run = async () => {
   if (!process.env.NPM_AUTH_TOKEN) throw new Error('Merge-release requires NPM_AUTH_TOKEN')