fix(deps): lift msgspec cap to 0.21.1 on py3.10+ for py3.13 concurrent-decode segfault (CNCT-85)

[fyzanshaik-atlan]

TL;DR

pyatlan caps msgspec<0.21. msgspec 0.20.0 has a native segfault on Python 3.13+ under concurrent JSON decode (msgspec #989 / #960), fixed in 0.21.0/0.21.1. SDK >=3.23.0 validates transformed assets by decoding pyatlan assets concurrently on every upload(), so on py3.13 it hits the msgspec bug and hard-crashes the worker. Because pyatlan pins below the fix, apps can only adopt it via a per-app override-dependencies hack (atlan-mssql-app PR #214). This lifts the cap so the fix is available cleanly.

Issue: CNCT-85.

What changed

- "msgspec~=0.20.0",
+ "msgspec~=0.20.0; python_version < '3.10'",
+ "msgspec~=0.21.1; python_version >= '3.10'",

A marker split, not a blanket bump. pyatlan supports and CI-tests Python 3.9, but msgspec 0.21's floor is 3.10 — a straight bump would silently drop 3.9. So 3.9 stays on 0.20.x (it can't hit the py3.13 segfault anyway) and everything >=3.10 gets 0.21.1.

Side benefit: py3.14 previously resolved to no msgspec at all (0.20 had no 3.14 wheels), which left pyatlan_v9 unusable there. 0.21.1 covers 3.10-3.14, so this fixes 3.14 too.

Commits

1. chore(deps): sync requirements.txt with uv.lock — the committed uv.lock was already current (cryptography 49.0.0, <3.15 markers) but requirements.txt was stale (46.0.5, <3.14). Regenerating it for the msgspec change unavoidably corrects that pre-existing drift, so it's isolated in its own commit to keep commit 2 surgical.
2. fix(deps): lift msgspec cap to 0.21.1 on py3.10+ ... — the pyproject split above, plus uv.lock (adds the 0.21.1 entry) and the 2 msgspec lines in requirements.txt.

Verification

• Full v9 unit suite: 7190 passed, 5 skipped, 0 failed on 0.21.1.
• Exercised the exact crash frames — Column.from_json -> serde.decode(ColumnNested) through the shared Serde singleton, 2000 concurrent decodes — all correct.
• uv lock --check consistent.

Caveat: this proves API compatibility. The segfault itself only reproduces on native Linux x86 under concurrent load (not macOS arm64), so the fix's efficacy rests on the msgspec #960 change plus the mssql-app CI repro.

Follow-ups (not in this PR)

• application-sdk: interim, flip VALIDATE_ASSETS_ON_UPLOAD default to false until the floor is safe; after this releases, bump the SDK's pyatlan floor and flip it back on.
• atlan-mssql-app: drop the override-dependencies once this is released.

[linear]

CNCT-85