🏄🏻‍♂️ Update github action to Ubuntu20.04

.github/workflows/python-package.yml

@@ -17,7 +17,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version: [ "3.7", "3.8" ]
-        os: [ ubuntu-18.04 ]
+        os: [ ubuntu-20.04 ]
 
     steps:
       - uses: actions/checkout@v3
@@ -35,15 +35,8 @@ jobs:
           pip install .
           
           sudo apt install -qqy lsb-release gnupg2 curl
-          echo "deb [arch=amd64] http://robotpkg.openrobots.org/packages/debian/pub $(lsb_release -cs) robotpkg" | sudo tee /etc/apt/sources.list.d/robotpkg.list
-          curl http://robotpkg.openrobots.org/packages/debian/robotpkg.key | sudo apt-key add -
           sudo apt-get update
-          sudo apt install -qqy robotpkg-py3*-pinocchio
-          export PATH=/opt/openrobots/bin:$PATH
-          export PKG_CONFIG_PATH=/opt/openrobots/lib/pkgconfig:$PKG_CONFIG_PATH
-          export LD_LIBRARY_PATH=/opt/openrobots/lib:$LD_LIBRARY_PATH
-          export CMAKE_PREFIX_PATH=/opt/openrobots:$CMAKE_PREFIX_PATH
       - name: Test with pytest
         run: |
           cd tests
-          pytest test_*.py --doctest-modules --junitxml=junit/test-results.xml --cov=com --cov-report=xml --cov-report=html
+          pytest test_*.py --doctest-modules --junitxml=junit/test-results.xml --cov=com --cov-report=xml --cov-report=html