Bump codecov/codecov-action from 3 to 4

Bumps [codecov/codecov-action](https://github.com/codecov/codecov-action) from 3 to 4.
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@v3...v4)

---
updated-dependencies:
- dependency-name: codecov/codecov-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/tests.yml

@@ -173,7 +173,7 @@ jobs:
           conda activate pymc-test
           python -m pytest -vv --cov=pymc --cov-report=xml --no-cov-on-fail --cov-report term --durations=50 $TEST_SUBSET
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }} # use token for more robust uploads
           env_vars: TEST_SUBSET
@@ -249,7 +249,7 @@ jobs:
           conda activate pymc-test &&
           python -m pytest -vv --cov=pymc --cov-report=xml --no-cov-on-fail --cov-report term --durations=50 %TEST_SUBSET%
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }} # use token for more robust uploads
           env_vars: TEST_SUBSET
@@ -328,7 +328,7 @@ jobs:
         run: |
           python -m pytest -vv --cov=pymc --cov-report=xml --no-cov-on-fail --cov-report term --durations=50 $TEST_SUBSET
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }} # use token for more robust uploads
           env_vars: TEST_SUBSET
@@ -396,7 +396,7 @@ jobs:
         run: |
           python -m pytest -vv --cov=pymc --cov-report=xml --no-cov-on-fail --cov-report term --durations=50 $TEST_SUBSET
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }} # use token for more robust uploads
           env_vars: TEST_SUBSET
@@ -468,7 +468,7 @@ jobs:
           conda activate pymc-test &&
           python -m pytest -vv --cov=pymc --cov-report=xml --no-cov-on-fail --cov-report term --durations=50 %TEST_SUBSET%
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }} # use token for more robust uploads
           env_vars: TEST_SUBSET