Refactor GitHub Actions workflow to install LaTeX dependencies and build document directly, updating artifact upload step

.github/workflows/main.yml

@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ main ]
 
+env:
+  PDF_NAME: Tesi.pdf
+
 jobs:
   build_latex:
     runs-on: ubuntu-latest
@@ -26,9 +29,9 @@ jobs:
 
       - name: Build LaTeX document
         run: |
-          pdflatex -interaction=nonstopmode -halt-on-error Tesi.tex || (cat /root/.miktex/texmfs/data/miktex/log/pdflatex.log && exit 1)
+          pdflatex -interaction=nonstopmode -halt-on-error ${{ env.PDF_NAME }} || (cat /root/.miktex/texmfs/data/miktex/log/pdflatex.log && exit 1)
 
       - name: Upload PDF artifact
         uses: actions/upload-artifact@v4
         with:
-          path: Test.pdf
+          path: ${{ env.PDF_NAME }}