Bump org.jetbrains.kotlin:kotlin-gradle-plugin-api from 2.0.0 to 2.0.21 in /devtools/gradle #2479

Job	Run time
CI Sanity Check	32s
Initial JDK 17 Build	13m 2s
Attach pull request number	4s
Calculate Test Jobs	9s
JVM Tests - JDK 17	7m 47s
JVM Tests - JDK 21	8m 45s
Gradle Tests - JDK 17	29m 46s
JVM Tests - JDK 17 Windows	10m 14s
Devtools Tests - JDK ${{ matrix.java.name }}	0s
Gradle Tests - JDK 17 Windows	47m 33s
Maven Tests - JDK ${{ matrix.java.name }}	0s
Quickstarts Compilation - JDK 17	6m 5s
Kubernetes Tests - JDK ${{ matrix.java.name }}	0s
Native Tests - Misc4	18m 47s
MicroProfile TCKs Tests	0s
Native Tests - Virtual Thread - ${{ matrix.category }}	0s
Upload build stats to collector	0s
Build report	28s
	2h 23m 12s

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