Bump actions/setup-python from 3 to 4 (#769)

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 3 to 4.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](actions/setup-python@v3...v4)

---
updated-dependencies:
- dependency-name: actions/setup-python
  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/main.yml

@@ -23,7 +23,7 @@ jobs:
 
     steps:
       - uses: "actions/checkout@v3"
-      - uses: "actions/setup-python@v3"
+      - uses: "actions/setup-python@v4"
 
         with:
           python-version: "${{ matrix.python-version }}"
@@ -40,7 +40,7 @@ jobs:
 
       # We always use a modern Python version for combining coverage to prevent
       # parsing errors in older versions for modern code.
-      - uses: "actions/setup-python@v3"
+      - uses: "actions/setup-python@v4"
         with:
           python-version: "3.8"
 
@@ -64,7 +64,7 @@ jobs:
 
     steps:
       - uses: "actions/checkout@v3"
-      - uses: "actions/setup-python@v3"
+      - uses: "actions/setup-python@v4"
 
         with:
           python-version: "3.8"
@@ -91,7 +91,7 @@ jobs:
 
     steps:
       - uses: "actions/checkout@v3"
-      - uses: "actions/setup-python@v3"
+      - uses: "actions/setup-python@v4"
 
         with:
           python-version: "3.8"