OPENQASM 3.1; is rejected as an unsupported version #397

Limitation

The current OpenQASM specification is version 3.1, and the
version string section defines the
OPENQASM M.m; header where the minor version is optional.

pyqasm hard-codes the accepted set to {"2", "2.0", "3", "3.0"}, so any program declaring
itself as 3.1 is refused before analysis begins.

Example QASM failure

OPENQASM 3.1;
include "stdgates.inc";
qubit[1] q;
h q[0];

ValidationError: Unsupported OpenQASM version: 3.1.
                 Supported versions are: {'2', '2.0', '3', '3.0'}

The identical program with OPENQASM 3.0; validates and unrolls without issue, so nothing
beyond the header check is involved.

Change Requested

1. Accept 3.1 alongside 3 and 3.0.
2. Prefer a comparison over an enumerated set: accept any 3.x and reject 4.x and above with
   a message that names the highest supported major version. That way the next minor release
   does not require another patch.
3. Preserve the declared version through dumps() — a program that comes in as 3.1 must go out
   as 3.1, since the existing "preserve QASM version" behaviour ([FEATURE] Preserve QASM version #36) is relied on downstream.
4. Update the README and docs, which currently state OpenQASM 3.0 support.

Implementation Details

• The check is in src/pyqasm/entrypoint.py:158, against the SUPPORTED_QASM_VERSIONS
  constant.
• The module classes in src/pyqasm/modules/ (qasm2.py, qasm3.py) dispatch on the parsed
  version; confirm that a 3.1 header routes to Qasm3Module and that the version string is
  stored verbatim for serialisation rather than normalised to 3.0.
• Worth stating explicitly in the issue resolution: accepting the 3.1 header does not by itself
  mean full 3.1 semantic coverage. This change removes a blanket rejection so that 3.1-tagged
  programs can be analysed; the remaining coverage gaps are tracked in the companion issues
  filed alongside this one.
• Tests: tests/test_entrypoint.py — OPENQASM 3.1; loads, unrolls, and round-trips with the
  version preserved; OPENQASM 4.0; still raises a ValidationError.