Specify the full path for pip3

Ensure that we are using the system Python environment. This aligns
with what we do in other roles, the needs of the cisagov/cyhy-runner
package, and the configuration in this role. The molecule testing
configuration is also updated to ensure it uses the system Python
environment.

Author: mcdonnnj

molecule/default/tests/test_default.py

@@ -36,7 +36,7 @@ def test_packages(host):
 @pytest.mark.parametrize("pkg", ["cyhy-runner"])
 def test_pip_packages(host, pkg):
     """Test that the pip packages were installed."""
-    assert pkg in host.pip.get_packages(pip_path="pip3")
+    assert pkg in host.pip.get_packages(pip_path="/usr/bin/pip3")
 
 
 @pytest.mark.parametrize(

tasks/main.yml

@@ -16,7 +16,7 @@
 
 - name: Install the cyhy-runner package
   ansible.builtin.pip:
-    executable: pip3
+    executable: /usr/bin/pip3
     # The extra argument is necessary on modern platforms, which
     # correctly recognize that the local Python is externally managed
     # (i.e. managed via the system package manager and not by pip).