Bump actions/checkout from 4 to 6 (#4)

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to
6.

Author: dependabot[bot]

.github/workflows/fly-deploy.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     concurrency: deploy-group    # optional: ensure only one action runs at a time
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: superfly/flyctl-actions/setup-flyctl@master
       - run: flyctl deploy --remote-only
         env:

.github/workflows/go.yml

@@ -14,7 +14,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
 
     - name: Set up Go
       uses: actions/setup-go@v5