Support python 3.13, drop 3.7

Author: davet2001

.github/workflows/ci.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python ${{ matrix.python-version }}

README.md

@@ -347,7 +347,7 @@ as seen on [Google+](https://plus.google.com/105569853186899442987/posts/N9T7xAj
 
 # Compatibility with Python versions
 
-This should work on Python 3.7 and above. It was tested with Python 3.7, 3.8, 3.9, 3.10, 3.11, 3.12.
+This should work on Python 3.8 and above. It was tested with Python 3.8, 3.9, 3.10, 3.11, 3.12, 3.13.
 
 # Authors