Update to actions/checkout@v6

Signed-off-by: David Crosby <dcrosby@fb.com>

Author: dafyddcrosby

.github/workflows/lint.yml

@@ -15,7 +15,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: 3.1

.github/workflows/unit-test.yml

@@ -16,7 +16,7 @@ jobs:
         experimental: [false]
     name: Unit testing with Ruby ${{ matrix.ruby }} on ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v6
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}