zizmor: set persist-credentials

per zizmor, actions/checkout should be followed by removal of credentials that
may have been saved to disk. Doing so fixes lots of whining such as:

```
warning[artipacked]: credential persistence through GitHub Actions artifacts
  --> ./.github/workflows/android.yml:27:9
   |
27 |         - name: "Checkout repository"
   |  _________^
28 | |         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
   | |________________________________________________________________________________^ does not set persist-credentials: false
   |
   = note: audit confidence → Low
   = note: this finding has an auto-fix
```

1 files changed, 4 insertions, 0 deletions

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 4fbe987..a2a85e7 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -48,6 +48,8 @@ jobs:
     steps:
       - name: "Checkout repository"
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
 
       - name: "Install test dependencies"
         run: |
@@ -100,6 +102,8 @@ jobs:
     steps:
       - name: "Checkout repository"
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
 
       - name: "Install test dependencies"
         run: |