removed build script usage from why2-project workflow

"Think before you remove somethin"

.github/workflows/why2-project.yml

@@ -15,7 +15,6 @@ jobs:
         include:
           - os: ubuntu-latest
             configure: configure.sh
-            build: build.sh
             test: test
 
     steps:
@@ -33,13 +32,12 @@ jobs:
       - name: Permissions
         run: |
           chmod +x ${{ matrix.configure }}
-          chmod +x ${{ matrix.build }}
 
       - name: Preparation
         run: sudo ./${{ matrix.configure }}
 
       - name: Install WHY2
-        run: sudo ./${{ matrix.build }} install
+        run: sudo make install
 
       - name: Download WHY2 test project
         run: curl -L -o ${{ matrix.test }}.c https://gist.github.com/ENGO150/d8419b6c31ffb68ebb930a5b41af8c73/raw