chore(deps): freshen dependency floors (2026-07)

Raise runtime and dev-tool constraint floors to eliminate stale/vulnerable
versions while preserving published behavior (61 tests green, ruff unchanged).

- nostrkey>=0.3.0 -> >=0.3.4 (latest upstream fixes)
- pytest>=8.0 -> >=8.4
- pytest-asyncio>=0.23 -> >=0.24
- ruff>=0.4 -> >=0.9

pip-audit: 9 vulns (cryptography+pip) -> 4 vulns. The 4 remaining are all
cryptography, blocked upstream by nostrkey's own cryptography<45.0 ceiling;
cannot be fixed from this repo without loosening nostrkey's pin.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QsXEE7WpEoLjVzgtUtq8jD

Author: vveerrgg

pyproject.toml

@@ -33,14 +33,14 @@ classifiers = [
     "Topic :: Software Development :: Libraries :: Python Modules",
 ]
 dependencies = [
-    "nostrkey>=0.3.0",
+    "nostrkey>=0.3.4",
 ]
 
 [project.optional-dependencies]
 dev = [
-    "pytest>=8.0",
-    "pytest-asyncio>=0.23",
-    "ruff>=0.4",
+    "pytest>=8.4",
+    "pytest-asyncio>=0.24",
+    "ruff>=0.9",
 ]
 
 [project.urls]