Fixed angle convention.

[emlynsg]

Example:
Previous to this PR, I was getting >12.0 for the angle when running the following code:

from graphix_qasm_parser import OpenQASMParser
s = """
    include "qelib1.inc";
    qubit q;
    rz(5*pi/4) q;
"""
parser = OpenQASMParser()
circuit = parser.parse_str(s)
pattern = circuit.transpile().pattern
print(pattern)

This update sets the value of ANGLE_PI depending on the version of Graphix in use.
The problem was missed before because the test comparison used the same pi scaling for both terms being compared.

The PR also updates the README of the repo to accurately reflect the supported gates and their equivalent instructions.

[thierry-martinez]

pyright fails because ANTLR parsers are not properly typed. I think it would be best to remove pyright from .github/workflows/typecheck.yml.

[thierry-martinez]

I would prefer ANGLE_PI to be imported from graphix.fundamentals.