⬆️ dep-bump: cap unxt below 2.0 (#800)

galax declares `unxt>=1.11.2` with no upper bound, but has never been resolved
or tested against unxt 2.x -- the lock has only ever held a 1.x. Today nothing
declares that boundary: `uv` considers unxt 2.0.0 during resolution (it is
compatible on `requires-python`) and backtracks to 1.11.x for transitive
reasons. That is incidental, not a guarantee, and it disappears the moment the
surrounding constraints shift.

Make the tested boundary explicit. The resolved version is unchanged --
1.11.2, as before -- so this is metadata only; `uv.lock` records the new
specifier and nothing else.

There is a concrete change coming that this guards against. unxt is making unit
system `repr`/`str` round-trippable
(GalacticDynamics/unxt#855), which rewrites the
`LTMAUnitSystem( length=Unit("kpc"), ...)` form that 32 doctest lines here pin,
18 of them in `_interop/galax_interop_gala/potential.py` and 12 in
`..._galpy/potential.py`. Those updates belong with the port to unxt 2.x, not
ahead of it.

Lift this cap in the PR that does that port.

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: nstarman

pyproject.toml

@@ -51,7 +51,7 @@ dependencies = [
   "quaxed>=0.10.5",
   "tfp-nightly[jax]>=0.25.0",
   "typing-extensions>=4.13.2",
-  "unxt>=1.11.2",
+  "unxt>=1.11.2,<2",
   "wadler_lindig>=0.1.7",
   "xmmutablemap>=0.2.1",
   "zeroth>=1.2.0",