Support for Python 3.13 (#1338)

Now that we've updated to (go)jsonnet 0.21, there's no remaining
blockers for supporting Python 3.13. I've updated the references to
supported Python versions that I found when grepping for `3.12`.

## Proposed Changes

* Bump maximum supported Python version to 3.13
* Update GitHub actions to cover Python 3.13
* Update bug report issue template supported Python versions

## Docs and Tests

* [ ] Tests added
* [x] Updated documentation

Author: simu

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -76,9 +76,10 @@ body:
     attributes:
       label: Version (Python)
       description: |
-        Which version of python are you using? Kapitan officially supports only version 3.10 and 3.11
+        Which version of Python are you using? Kapitan officially supports versions 3.10 - 3.13
         If you are using an older version of python, please check if the bug still exists with a newer (supported) version.
       options:
+        - "3.13"
         - "3.12"
         - "3.11"
         - "3.10"

.github/workflows/pex-build-upload.yml

@@ -26,6 +26,7 @@ jobs:
             3.10
             3.11
             3.12
+            3.13
       - name: Install libraries dependencies
         run: |
           poetry export --without-hashes --format=requirements.txt > requirements.txt
@@ -45,6 +46,7 @@ jobs:
             --python=python3.11 \
             --python=python3.10 \
             --python=python3.12 \
+            --python=python3.13 \
             -m kapitan \
             -o dist/kapitan.linux-x86_64.pex
           dist/kapitan.linux-x86_64.pex --help

.github/workflows/test-build-publish.yml

@@ -45,7 +45,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ['3.10', '3.11', '3.12']
+        python-version: ['3.10', '3.11', '3.12', '3.13']
     steps:
       - name: Checkout kapitan recursively
         uses: actions/checkout@v4