Update all non-major dependencies

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
net.md-5:bungeecord-api	1.19-R0.1-SNAPSHOT → 1.21-R0.4
org.apache.maven.plugins:maven-shade-plugin (source)	3.4.0 → 3.6.2
org.apache.maven.plugins:maven-shade-plugin (source)	3.3.0 → 3.6.2
org.apache.maven.plugins:maven-compiler-plugin (source)	3.8.1 → 3.15.0
com.velocitypowered:velocity-api (source)	3.1.1 → 3.4.0

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