chore: Drop python 3.7, add python 3.13 support

The Ubuntu GH runners don't have python 3.7 anymore, so dropping as EoL.

Author: catanzaromj

.github/workflows/python-test.yml

@@ -14,7 +14,7 @@ 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@v4

persim/_version.py

@@ -1 +1 @@
-__version__ = "0.3.7"
+__version__ = "0.3.8"