Update release prep action

Rename the action to "Release Prep" (better matches what it does) and
also provide an optional input value which can be used to supply a
GitHub personal access token, in order to avoid throttled API request
to GitHub when using github-changelog-generator.

Author: reidmv

.github/workflows/auto_release.yml renamed to .github/workflows/release_prep.yml

@@ -1,12 +1,15 @@
-name: "Auto release"
+name: "Release Prep"
 
 on:
   workflow_dispatch:
+    inputs:
+      personal_access_token:
+        description: 'GitHub Personal Access Token'
+        required: false
 
 env:
   HONEYCOMB_WRITEKEY: 7f3c63a70eecc61d635917de46bea4e6 
   HONEYCOMB_DATASET: litmus tests
-  CHANGELOG_GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
 jobs:
   auto_release:
@@ -38,7 +41,7 @@ jobs:
       with:
         args: 'release prep --force'
       env:
-        CHANGELOG_GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        CHANGELOG_GITHUB_TOKEN: "${{ github.event.inputs.personal_access_token }}"
 
     - name: "Get Version"
       if: ${{ github.repository_owner == 'puppetlabs' }}