fix(jmap): replace deprecated pytz with stdlib zoneinfo in jscal_to_ical

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Author: SashankBhamidi

pyproject.toml

@@ -102,7 +102,6 @@ ignore = ["DEP002"]  # Test dependencies (pytest, coverage, etc.) are not import
 
 [tool.deptry.per_rule_ignores]
 DEP001 = ["conf", "h2"]  # conf: Local test config, h2: Optional HTTP/2 support
-DEP003 = ["pytz"]  # Optional timezone library; imported inside try/except with graceful fallback
 
 [tool.ruff]
 line-length = 100