Fix pytest test collection on default install

As is, with a default `poetry install`, a simple `poetry pytest run`
will encouter import errors while reading the test files themselves --
which causes pytest to fatally error during test collection, meaning no
tests are run.

meshtastic/tests/test_analysis.py

@@ -6,7 +6,11 @@ import sys
 
 import pytest
 
-from meshtastic.analysis.__main__ import main
+try:
+    # Depends upon matplotlib & other packages in poetry's analysis group, not installed by default
+    from meshtastic.analysis.__main__ import main
+except ImportError:
+    pytest.skip("Can't import meshtastic.analysis", allow_module_level=True)
 
 
 @pytest.mark.unit