ci: disable credential persistence on checkout steps

Set persist-credentials: false on all six actions/checkout steps. These
jobs run untrusted PR code via cargo and docker build, and checkout's
default leaves the GITHUB_TOKEN in the local git config where that code
could read it. None of the jobs push or otherwise need git credentials.

Author: beardthelion

.github/workflows/pr-checks.yml

@@ -26,6 +26,8 @@ jobs:
     steps:
       - name: Check out repository
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: false
 
       - name: Set up Rust toolchain
         uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # stable
@@ -55,6 +57,8 @@ jobs:
     steps:
       - name: Check out repository
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: false
 
       - name: Set up Rust toolchain
         uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # stable
@@ -76,6 +80,8 @@ jobs:
     steps:
       - name: Check out repository
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: false
 
       - name: Set up Rust toolchain
         uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # stable
@@ -97,6 +103,8 @@ jobs:
     steps:
       - name: Check out repository
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: false
 
       - name: Set up Rust toolchain
         uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # stable
@@ -121,6 +129,8 @@ jobs:
     steps:
       - name: Check out repository
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: false
 
       - name: Set up Rust 1.91
         uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # 1.91
@@ -142,6 +152,8 @@ jobs:
     steps:
       - name: Check out repository
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: false
 
       - name: Build image
         run: docker build -t gitlawb-node:ci-test .