chore: Release 5.5.4

[onesignal-deploy]

Channels: Current

🐛 Bug Fixes

• fix(android): unsubscribe click listener when Flutter engine detaches (fix(android): unsubscribe click listener when Flutter engine detaches #1140)

[claude]

LGTM — straightforward version bump from 5.5.3 to 5.5.4.

Extended reasoning...

Overview

This PR bumps the SDK version from 5.5.3 to 5.5.4 across all five expected locations: pubspec.yaml, android/build.gradle, ios/onesignal_flutter.podspec, the Android OneSignalPlugin.java (setSdkVersion("050504")), and the iOS OneSignalPlugin.m (sdkVersion = @"050504"). Version strings are consistent everywhere (5.5.4 in human-readable form, 050504 in the encoded SDK form). The release rolls up a single bug fix already merged on main (#1140 — unsubscribing the click listener on Flutter engine detach).

Security risks

None. No logic changes, no new dependencies, no auth/crypto/permissions touched — purely string version updates.

Level of scrutiny

Minimal. This is a mechanical release PR with no behavioral changes. The underlying bug fix has already been reviewed and merged separately.

Other factors

No outstanding reviewer comments. No prior reviews from me on this PR. Version numbers are internally consistent across all five files.