Bump actions/checkout from 1 to 4 (#140)

Bumps [actions/checkout](https://github.com/actions/checkout) from 1 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v1...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/doc.yaml

@@ -13,7 +13,7 @@ jobs:
   docs:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: jiro4989/setup-nim-action@v1
         with:
           nim-version: 'devel'

.github/workflows/test.yaml

@@ -23,7 +23,7 @@ jobs:
           - 'devel'
     needs: before
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v4
       - uses: jiro4989/setup-nim-action@v1
         with:
           nim-version: ${{ matrix.nim-version }}