Update workflows to get python version from pyproject.toml

Author: frances-h

.github/workflows/dependency_checker.yml

@@ -8,10 +8,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
-    - name: Set up Python 3.9
+    - name: Set up latest Python
       uses: actions/setup-python@v5
       with:
-        python-version: 3.9
+        python-version-file: 'pyproject.toml'
     - name: Install dependencies
       run: |
         python -m pip install .[dev]

.github/workflows/lint.yml

@@ -10,10 +10,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
-    - name: Set up Python 3.9
+    - name: Set up latest Python
       uses: actions/setup-python@v5
       with:
-        python-version: 3.9
+        python-version-file: 'pyproject.toml'
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip

.github/workflows/prepare_release.yml

@@ -19,10 +19,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: Set up Python 3.10
+      - name: Set up latest Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.10'
+          python-version-file: 'pyproject.toml'
 
       - name: Install dependencies
         run: |