Fix venv recreation after Python version change

After an OS upgrade, the Python version may change but the existing
virtualenv at /opt/borgmatic still references the old Python binary.
This causes ModuleNotFoundError when trying to run borgmatic.

This fix adds checks before venv creation to:
1. Get the system's current Python version
2. Check the Python version in the existing venv (if any)
3. Remove the venv if versions don't match, allowing it to be recreated

Fixes #113

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tasks/noauto_install_pip.yml

@@ -12,6 +12,25 @@
         name: "{{ borg_pip_packages }}"
         state: present
 
+    - name: Get system Python version
+      ansible.builtin.command: "{{ python_bin }} --version"
+      register: borg_system_python_version
+      changed_when: false
+
+    - name: Check Python version in existing borgmatic venv
+      ansible.builtin.command: "{{ borg_venv_path }}/bin/python --version"
+      register: borg_venv_python_version
+      failed_when: false
+      changed_when: false
+
+    - name: Remove borgmatic venv if Python version doesn't match
+      ansible.builtin.file:
+        path: "{{ borg_venv_path }}"
+        state: absent
+      when:
+        - borg_venv_python_version.rc == 0
+        - borg_venv_python_version.stdout != borg_system_python_version.stdout
+
     - name: Create virtualenv for borg  # noqa package-latest
       ansible.builtin.pip:
         name: