fix CQL2 parsing of NOT filters

[tomkralidis]

As per https://docs.ogc.org/is/21-065r2/21-065r2.html#_conformance_test_14 :

Testing with pygeofilter CLI (main branch):

$ pygeofilter parse cql2_text "NOT(name LIKE '%lake%')"
Parsing cql2_text query into AST
Error: Unexpected token Token('LIKE', 'LIKE') at line 1, column 10.
Expected one of: 
	* RPAR

$ pygeofilter parse cql2_text "NOT(foo=0)"
Parsing cql2_text query into AST
Error: Unexpected token Token('EQUAL', '=') at line 1, column 8.
Expected one of: 
	* RPAR

$ pygeofilter parse cql2_text "NOT(foo>0)"
Parsing cql2_text query into AST
Error: Unexpected token Token('MORETHAN', '>') at line 1, column 8.
Expected one of: 
	* RPAR

Originally posted by @tomkralidis in pygeoapi #2099