ci: Do not persist credentials after checkout (#221)

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/build-and-test.yaml

@@ -43,6 +43,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           ref: ${{ inputs.ref || (github.event.number && format('refs/pull/{0}/merge', github.event.number)) }}
+          persist-credentials: false
 
       - name: Configure Build Matrix
         id: configure
@@ -96,6 +97,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ inputs.ref || (github.event.number && format('refs/pull/{0}/merge', github.event.number)) }}
+          persist-credentials: false
 
       - name: Set Python version
         uses: actions/setup-python@v5

.github/workflows/publish-docs.yaml

@@ -32,6 +32,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ inputs.ref || github.ref }}
+          persist-credentials: false
 
       - name: Set Python version
         uses: actions/setup-python@v5