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

.github/workflows/main.yml

@@ -7,7 +7,6 @@ on:
     branches: [ main ]
 
 env:
-  TEX_NAME: Tesi.tex
   PDF_NAME: Tesi.pdf
 
 jobs:
@@ -30,7 +29,7 @@ jobs:
 
       - name: Build LaTeX document
         run: |
-          pdflatex -interaction=nonstopmode -halt-on-error ${{ env.TEX_NAME }} || (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