Fix RespawnPacket import order to unblock the Velocity-CTD sync build

[ssquadteam]

Resolves #23.

The automated Velocity-CTD libdeflate sync merged abfbb372de41480b93cb31b2400c7a304998083d cleanly, but ./gradlew build failed on the merged tree, so no pull request was opened.

Cause

The merge only carried three dependency bumps in gradle/libs.versions.toml — no code changes:

• spotless 8.9.0 → 8.10.0
• checkstyle 13.10.0 → 13.11.0
• guava 33.6.0-jre → 33.7.0-jre

The failing task is :velocity-proxy:checkstyleMain, which reports two CustomImportOrderCheck warnings in BackendPlaySessionHandler.java. Because velocity-checkstyle.gradle.kts sets maxWarnings = 0, those warnings fail the build:

Wrong lexicographical order for 'com.velocitypowered.proxy.protocol.packet.ResourcePackRequestPacket' import.
Should be before 'com.velocitypowered.proxy.protocol.packet.RespawnPacket'.

The RespawnPacket import was added ahead of the ResourcePack* imports. That is the wrong slot — Resp sorts after Reso in ASCII — and checkstyle 13.11.0 tightened CustomImportOrderCheck so it now flags what 13.10.0 let through. The defect is on main; the sync merge only exposed it.

Fix

Move the RespawnPacket import below ResourcePackResponsePacket. One line, no behaviour change.

Verification

• ./gradlew build on this branch (checkstyle 13.10.0): BUILD SUCCESSFUL, :velocity-proxy:checkstyleMain executed fresh.
• ./gradlew build on main + the libdeflate merge + this fix (checkstyle 13.11.0): BUILD SUCCESSFUL, :velocity-proxy:checkstyleMain and :velocity-proxy:test both executed fresh.

Once this lands on main, the next upstream-sync run should merge libdeflate and open its pull request normally.