Fixing LESS, GREATER and IMPLIES operator, outdated typing.io imports and pastification of negative numbers

[tederer]

• Set version of antlr4 to 4.9 to get the typing fixes. Deleted StlLexer files because they are outdated and no grammar file (.g4) exists to build them with 4.9.
• Fixed typing import statements because typing.io is deprecated and removed since Python 3.13.
• Changed LESS and GREATER operator to return -sys.float_info.min when arguments are identical.
• Changed IMPLIES operator to use sys.float_info.max for the left argument when it is zero. This prevents implications that are always true, even when they should not be. Added some tests as well to document the original problem.
• Fixed pastification result when specification/rule contains a negative integer or decimal. Before this fix rules like "signal1 >= -3" or "signal1 >= -3.0" resulted in losing the sign of the "3"-literal.