.github/workflows: various fixes.

- don't try to `brew update-sponsors`, @BrewTestBot doesn't have
  `admin:org` rights, nor should they
- allow testing the `maintainers-man-completions` workflow on branches
- cache RubyGems for `brew generate-man-completions`
- add `workflow_dispatch` support to `spdx` workflow for easier testing

.github/workflows/maintainers-man-completions.yml

@@ -1,9 +1,9 @@
-name: Update sponsors, maintainers, manpage and completions
+name: Update maintainers, manpage and completions
 
 on:
   push:
     paths:
-      - .github/workflows/sponsors-maintainers-man-completions.yml
+      - .github/workflows/maintainers-man-completions.yml
       - README.md
       - Library/Homebrew/cmd/**
       - Library/Homebrew/dev-cmd/**
@@ -12,8 +12,6 @@ on:
       - Library/Homebrew/cli/parser.rb
       - Library/Homebrew/completions.rb
       - Library/Homebrew/env_config.rb
-    branches:
-      - master
   schedule:
     - cron: "0 0 * * *"
   workflow_dispatch:
@@ -27,6 +25,7 @@ jobs:
     if: github.repository == 'Homebrew/brew'
     steps:
       - name: Setup Homebrew
+        id: set-up-homebrew
         uses: Homebrew/actions/setup-homebrew@master
 
       - name: Configure Git user
@@ -39,12 +38,24 @@ jobs:
         with:
           signing_key: ${{ secrets.BREWTESTBOT_GPG_SIGNING_SUBKEY }}
 
-      - name: Update sponsors, maintainers, manpage and completions
+      - name: Cache Bundler RubyGems
+        uses: actions/cache@v1
+        with:
+          path: ${{ steps.set-up-homebrew.outputs.gems-path }}
+          key: ${{ runner.os }}-rubygems-${{ steps.set-up-homebrew.outputs.gems-hash }}
+          restore-keys: ${{ runner.os }}-rubygems-
+
+      - name: Update maintainers, manpage and completions
         id: update
         run: |
           git fetch origin
 
-          BRANCH=sponsors-maintainers-man-completions
+          if [[ -n "$GITHUB_REF_NAME" && "$GITHUB_REF_NAME" != "master" ]]
+          then
+            BRANCH="$GITHUB_REF_NAME"
+          else
+            BRANCH=maintainers-man-completions
+          fi
           echo "::set-output name=branch::${BRANCH}"
 
           if git ls-remote --exit-code --heads origin "${BRANCH}"
@@ -64,15 +75,7 @@ jobs:
                     "${GITHUB_WORKSPACE}/docs/Manpage.md" \
                     "${GITHUB_WORKSPACE}/manpages/brew.1"
             git commit -m "Update maintainers." \
-                       -m "Autogenerated by the [update-man-completions](https://github.com/Homebrew/brew/blob/HEAD/.github/workflows/sponsors-maintainers-man-completions.yml) workflow."
-            COMMITTED=true
-          fi
-
-          if brew update-sponsors
-          then
-            git add "${GITHUB_WORKSPACE}/README.md"
-            git commit -m "Update sponsors." \
-                       -m "Autogenerated by the [update-man-completions](https://github.com/Homebrew/brew/blob/HEAD/.github/workflows/sponsors-maintainers-man-completions.yml) workflow."
+                       -m "Autogenerated by the [update-man-completions](https://github.com/Homebrew/brew/blob/HEAD/.github/workflows/maintainers-man-completions.yml) workflow."
             COMMITTED=true
           fi
 
@@ -83,7 +86,7 @@ jobs:
                     "${GITHUB_WORKSPACE}/manpages/brew.1" \
                     "${GITHUB_WORKSPACE}/completions"
             git commit -m "Update manpage and completions." \
-                       -m "Autogenerated by the [update-man-completions](https://github.com/Homebrew/brew/blob/HEAD/.github/workflows/sponsors-maintainers-man-completions.yml) workflow."
+                       -m "Autogenerated by the [update-man-completions](https://github.com/Homebrew/brew/blob/HEAD/.github/workflows/maintainers-man-completions.yml) workflow."
             COMMITTED=true
           fi
 

.github/workflows/spdx.yml

@@ -7,8 +7,11 @@ on:
       - master
   schedule:
     - cron: "0 0 * * *"
+  workflow_dispatch:
+
 permissions:
   contents: read
+
 jobs:
   spdx:
     if: github.repository == 'Homebrew/brew'