Bump actions/setup-python from 5 to 6 (#1245)

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 5 to 6.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](actions/setup-python@v5...v6)

---
updated-dependencies:
- dependency-name: actions/setup-python
  dependency-version: '6'
  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/continuous_benchmarking_master_branch.yml

@@ -17,7 +17,7 @@ jobs:
 
       # Setup Python version
       - name: Setup Python 3.9
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: 3.9
 

.github/workflows/continuous_benchmarking_pull_requests.yml

@@ -24,7 +24,7 @@ jobs:
 
       # Setup Python version
       - name: Setup Python 3.9
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: 3.9
 

.github/workflows/nestml-build.yml

@@ -30,7 +30,7 @@ jobs:
 
       # Setup Python version
       - name: Setup Python 3.9
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: 3.9
 
@@ -61,7 +61,7 @@ jobs:
 
       # Setup Python version
       - name: Setup Python 3.9
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: 3.9
 
@@ -128,7 +128,7 @@ jobs:
 
       # Setup Python version
       - name: Setup Python 3.9
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: 3.9
 
@@ -176,7 +176,7 @@ jobs:
 
       # Setup Python version
       - name: Setup Python 3.9
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: 3.9
 
@@ -312,7 +312,7 @@ jobs:
 
       # Setup Python version
       - name: Setup Python 3.9
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: 3.9
 
@@ -376,7 +376,7 @@ jobs:
 
       # Setup Python version
       - name: Setup Python 3.9
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: 3.9