fix: use increase versioning-strategy for uv dependabot updates

[hcallahan-lowrisc]

Problem

Every Dependabot PR that bumps a direct Python dependency currently ships a broken pyproject.toml. The uv updater's default (widen-flavoured) strategy collapses a bounded requirement into an invalid PEP 508 string — e.g. in #262 it rewrote:

-    "gitpython>=3.1.58",
+    "gitpython*",

"gitpython*" is not valid PEP 508 (a bare * with no operator), so CI fails at the install step for every job:

error: Failed to generate package metadata for `dvsim ... editable+.`
  ValueError: Dependency #4 of field `project.dependencies` is invalid:
    Expected semicolon (after name with no version specifier) or end
      gitpython*

The generated uv.lock half is correct; only the manifest rewrite is broken. Transitive-only bumps are unaffected (they never touch pyproject.toml), which is why the failures look intermittent. To date these PRs have been merged only after hand-fixing each specifier.

This is upstream bug dependabot/dependabot-core#15639 (open).

Fix

Set versioning-strategy: increase on the uv update entry. versioning-strategy is supported for the uv ecosystem (uv's updater inherits Python's RequirementsUpdater). increase bumps the lower bound instead of widening — ">=3.1.58" → ">=3.1.59" — which is valid PEP 508, matches the manifest's existing floor style, and keeps floors from silently going stale.

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