Use pip rather than pip3

Author: Joseph-Edwards

.github/workflows/tests.yml

@@ -49,10 +49,10 @@ jobs:
       - name: "Python version . . ."
         run: |
           python --version
-          pip3 --version
-      - name: "Pip3 installing libsemigroups_pybind11 . . ."
+          pip --version
+      - name: "Pip installing libsemigroups_pybind11 . . ."
         run: |
-          CXX="${{ matrix.compiler }}" pip3 install . -v
+          CXX="${{ matrix.compiler }}" pip install . -v
       - name: "python -m pytest -vv tests/test_*.py . . ."
         run: |
           python -m pytest -vv tests/test_*.py
@@ -61,9 +61,9 @@ jobs:
           etc/make-doc.sh  # so that all files are generated!
           cd docs
           python -m sphinx -b doctest -d _build/doctrees source _build/doctest
-      - name: "Pip3 installing pylint + cpplint . . ."
+      - name: "Pip installing pylint + cpplint . . ."
         run: |
-          pip3 install pylint cpplint
+          pip install pylint cpplint
       - name: "Running pylint and cpplint . . ."
         run: |
           python -m pylint setup.py tests/*.py libsemigroups_pybind11/*.py