BUG: fix euality check on Graph

[martinfleis]

When doing Graph == not a graph, the check currently raises an AttributeError as show in pysal/esda#395. This fixes it and fixes pysal/esda#395.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.2%. Comparing base (e47859e) to head (ab8e529).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #809     +/-   ##
=======================================
- Coverage   85.4%   84.2%   -1.2%     
=======================================
  Files        150     150             
  Lines      15954   15956      +2     
=======================================
- Hits       13620   13430    -190     
- Misses      2334    2526    +192     

Files with missing lines	Coverage Δ
libpysal/graph/_set_ops.py	94.5% <100.0%> (ø)
libpysal/graph/tests/test_set_ops.py	100.0% <100.0%> (ø)

... and 4 files with indirect coverage changes

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[martinfleis]

CI failure unrelated.

[ljwolf]

Yes, the failing tests should probably be skipped, rather than failing due to missing pyproj.

[jGaboardi]

Yes, the failing tests should probably be skipped, rather than failing due to missing pyproj.

@ljwolf --> @sjsrey added this in 6471872 of #791