Bump twine to 7.0.0 so it accepts Metadata-Version 2.5

[imnasnainaec]

Two commits, both about the same drift: the build backend floats while the tools
around it are pinned.

1. twine 6.2.0 → 7.0.0

Build is red on main and on every open branch:

Checking dist/sil_lift-0.1.0-py3-none-any.whl: ERROR
  InvalidDistribution: Invalid distribution metadata:
  '2.5' is not a valid metadata version

[build-system] requires was unbounded, so python -m build resolves the
current hatchling into its isolated environment. Hatchling 1.32.0 emits
Metadata-Version: 2.5; the packaging bundled with the pinned twine==6.2.0
tops out below that. The distribution is fine — the checker is older than the
metadata standard the backend now writes.

Bumping the checker rather than pinning the backend keeps the distribution
current with the standard instead of freezing it at 2.4. release.yml runs the
same check before publishing to PyPI, so both workflows move together.

2. requires = ["hatchling>=1.27"]

The same unbounded requirement hides a second, quieter problem. license = "MIT"
with license-files is PEP 639, honored by hatchling from 1.27.0. An older
backend builds the wheel without complaint and emits the SPDX string as a legacy
free-text field, dropping License-Expression and License-File:

hatchling	Metadata-Version	License fields	twine check
1.26.3	2.3	License: MIT (legacy free-text)	PASSED
1.27.0	2.4	License-Expression: MIT + License-File: LICENSE	PASSED
1.32.0	2.5	same as 1.27.0	fails on twine 6.2.0 only

Note that twine check passes the degraded wheel — a build environment
resolving an older hatchling would publish this package as though it had no
machine-readable license, and nothing in CI would say so. The floor declares a
requirement the project already has.

A floor rather than a pin: redistributors build the sdist against their own
packaged hatchling, and an == here would force them to patch
pyproject.toml.

Verified locally with the floor in place: python -m build produces
Metadata-Version: 2.5 with License-Expression: MIT and
License-File: LICENSE; twine check passes wheel and sdist.

Nothing enforces this floor — as with every other >= in pyproject.toml.
Filed separately: a minimum-versions CI leg that would make all of them tested
claims, and which is where a license-metadata assertion belongs.

Once this lands, main merged forward turns Build green on #22 and #23,
which fail only there.

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