chore(deps): update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/docker.yml

@@ -15,7 +15,7 @@ jobs:
       packages: write
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: true
 

.github/workflows/update.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out code
-        uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
+        uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6
       - name: Download server
         run: | 
           wget -O ezproxy https://help.oclc.org/@api/deki/files/9850/ezproxy-linux.bin