[Fix] Fix overgeneralizaiton of var to varlist

[colinthebomb1]

Overview:

This PR reverts a fix in PR #77 that caused overgeneralization of vars to varlists, and instead fixes the root issue of a regex typo in fingerprinting that caused a variable to be infinitely generalized. It also fixes a minor regex issue in unify_variable_names that caused the <= sign in <x1> > <x2> AND <x1> <= <x2> to be seen as part of a variable.

Testing:

• Pass all existing tests under test
• Reintroduce test_generate_general_rule_8 and fixes test_generate_spreadsheet_id_4 tests

Issues:

close #80