ci: update checkout action to v6

Author: hyperfinitism

.github/workflows/lint.yml

@@ -12,7 +12,7 @@ jobs:
     name: rustfmt
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
           toolchain: stable
@@ -23,7 +23,7 @@ jobs:
     name: clippy
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
           toolchain: stable

.github/workflows/spdx.yml

@@ -13,7 +13,7 @@ jobs:
     name: spdx
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: enarx/spdx@master
       with:
         licenses: MIT

.github/workflows/test.yml

@@ -30,7 +30,7 @@ jobs:
             runner: macos-latest
             target: aarch64-apple-darwin
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
           toolchain: ${{ matrix.toolchain }}