ci: Do not persist credentials after checkout (#71)

See actions/checkout#485 and
https://johnstawinski.com/2024/01/11/playing-with-fire-how-we-executed-a-critical-supply-chain-attack-on-pytorch/

In short, it is a terrible idea to persist even our default credentials
after checkout. There's no call for that, so we will now set
`persist-credentials: false` on all checkout actions.

.github/workflows/release.yaml

@@ -25,6 +25,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: true
+          persist-credentials: false
 
       - name: Install deps
         run: |
@@ -99,6 +100,8 @@ jobs:
     runs-on: windows-latest
     steps:
       - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
 
       - name: Set version number
         shell: bash
@@ -196,6 +199,8 @@ jobs:
         with:
           repository: '${{ secrets.HOMEBREW_TAP_REPO }}'
           fetch-depth: 0  # The entire repo history, so we can push an update
+          # To push to this repo, an explicit token is used to authenticate.
+          persist-credentials: false
 
       - name: Wipe source and formula folders
         run: |
@@ -211,6 +216,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           path: shaka-lab-source
+          persist-credentials: false
 
       - name: Finish staging tap repo
         run: |