v2.3.0 Release

Minor updates:

• #254 - address nullability warnings from _GTMDevAssert
• #256 - Remove GTMWindowSheetController
• #261 - Create interface for initializing DB with SQLite flags
• #262- Add more context to some SQLite asserts
• #263 - SQLite userdata structures need to exist for lifetime of hooks
• #267 - Fix issue found via asan in GTMRegex

⚠️ Note: This is a minor version bump because GTMWindowSheetController was removed.