Defines a unique Python version (#2646)

# Description

Please provide a summary of the changes, including relevant motivation
and context.

Closes #(issue_number)

## Checklist

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have performed a self-review of my own code
- [ ] I have attached images of the change if it is UI based
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] If my code has heavily changed functionality I have updated
relevant docs on [Stirling-PDFs doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
- [x] My changes generate no new warnings
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

.github/workflows/check_properties.yml

@@ -28,7 +28,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@0b93645e9fea7318ecaed2b359559ac225c90a2b # v5.3.0
         with:
-          python-version: "3.x"
+          python-version: "3.12"
 
       - name: Get PR data
         id: get-pr-data

.github/workflows/sync_files.yml

@@ -28,7 +28,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@0b93645e9fea7318ecaed2b359559ac225c90a2b # v5.3.0
         with:
-          python-version: "3.x"
+          python-version: "3.12"
       - name: Install dependencies
         run: pip install tomlkit
       - name: Sync README

.github/workflows/update-translations.yml

@@ -28,7 +28,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@0b93645e9fea7318ecaed2b359559ac225c90a2b # v5.3.0
         with:
-          python-version: "3.x"
+          python-version: "3.12"
 
       - name: Run Python script to check files
         id: run-check