Clean CI following alpha release

Signed-off-by: Florian Dupuy <florian.dupuy@rte-france.com>

.github/workflows/maven.yml

@@ -17,12 +17,6 @@ jobs:
         os: [ubuntu-latest, windows-latest, macos-latest]
 
     steps:
-      - name: Checkout powsybl-core linked sources
-        uses: actions/checkout@v1
-        with:
-          repository: powsybl/powsybl-core
-          ref: refs/heads/dynamic_simulation_reporter
-
       - name: Checkout sources
         uses: actions/checkout@v1
 
@@ -31,9 +25,6 @@ jobs:
         with:
           java-version: 17
 
-      - name: Build and install powsybl-core with Maven
-        run: mvn --batch-mode -DskipTests=true --file ../powsybl-core/pom.xml install
-
       - name: Build with Maven
         if: matrix.os == 'ubuntu-latest'
         run: mvn --batch-mode -Pintegration-tests,jacoco install