Use venv pip (#821)

* Use venv Python pip

* Use default Netlify Python (3.12 for newest Ubuntu image)

Author: stefanv

Makefile

@@ -11,7 +11,7 @@ help:   ## show this help
 
 prepare:
 	git submodule update --init
-	((python -c 'import yaml2ics' && pre-commit) > /dev/null 2>&1) || pip install -q -r requirements.txt
+	((python -c 'import yaml2ics' && pre-commit) > /dev/null 2>&1) || python -m pip install -q -r requirements.txt
 	test -f .git/hooks/pre-commit || pre-commit install
 
 CALENDAR_DIR = content/calendars

netlify.toml

@@ -1,5 +1,4 @@
 [build.environment]
-  PYTHON_VERSION = "3.13"
   HUGO_VERSION = "0.141.0"
   DART_SASS_VERSION = "1.83.4"
   DART_SASS_URL = "https://github.com/sass/dart-sass/releases/download/"