ci: bump actions/checkout to v6

Node 20 used by v3 is being deprecated soon

Author: ignyx

.github/workflows/lint-test.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
         with:
           node-version: 24

.github/workflows/release.yaml

@@ -15,7 +15,7 @@ jobs:
     environment: build
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
         with:
           node-version: 24
@@ -61,7 +61,7 @@ jobs:
     environment: build-ios
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v3
         with:
           node-version: 24