chore(docker): Do not run pip install pip ... twice

There is another `pip install pip` call directly above, which properly
specifies the desired version.

Signed-off-by: Frank Viernau <frank_viernau@epam.com>

Dockerfile

@@ -159,7 +159,6 @@ RUN pip install --no-cache-dir -U \
     && pip install --no-cache-dir -U \
     Mercurial \
     conan=="$CONAN_VERSION" \
-    pip \
     pipenv=="$PYTHON_PIPENV_VERSION" \
     poetry=="$PYTHON_POETRY_VERSION" \
     python-inspector=="$PYTHON_INSPECTOR_VERSION"