fix: Use right python environment

Even despite adsf did activate python3.8. This was not used by poetry.
python-poetry/poetry#655

In the Make target I've added a command which ensures that the right python
version is used.

Author: Ecno92

Diff for: Makefile

@@ -10,6 +10,7 @@ publish:
 	$(POETRY_RUN) pelican
 
 venv:
+	poetry env use $(shell which python3)
 	poetry install
 
 deploy: venv theme publish

Diff for: pyproject.toml

@@ -6,7 +6,7 @@ authors = ["Therry van Neerven <[email protected]>"]
 readme = "README.md"
 
 [tool.poetry.dependencies]
-python = "^3.8"
+python = "^3.8.10"
 Markdown = "*"
 pelican = "*"
 markdown = "*"