Fix (hopefully) CI builds (#47)

This pull request:
- Changes dependency installation in CI to use `requirements.txt` file
- Adds missing pyparsing library

Resolves: #46

Author: Argmaster

.github/workflows/deploy.yml

@@ -20,7 +20,7 @@ jobs:
       - uses: actions/setup-python@v6
         with:
           python-version: 3.12
-      - run: pip install zensical
+      - run: pip install -r requirements.txt
       - run: zensical build --clean
       - uses: actions/upload-pages-artifact@v5
         with:

requirements.txt

@@ -1,3 +1,4 @@
 zensical==0.0.50
 jinja2>=3.1,<3.2
 pydantic>=2.13,<2.14
+pyparsing>=3.3.2,<3.4