chore: Bump scalameta to 4.12.7 #14623

Job	Run time
windows-latest jdk-17 unit tests 1 / 2	29m 46s
windows-latest jdk-17 unit tests 2 / 2	28m 22s
macOS-latest jdk-17 unit tests 1 / 2	57m 15s
macOS-latest jdk-17 unit tests 2 / 2	47m 18s
ubuntu-latest jdk-17 unit tests 1 / 2	18m 30s
Gradle MacOS integration	14m 17s
ubuntu-latest jdk-17 unit tests 2 / 2	17m 30s
Sbt integration	47m 0s
Maven integration	8m 34s
Gradle integration	9m 26s
Scala CLI integration	12m 23s
Mill integration	34m 39s
Bazel integration	10m 49s
LSP integration tests	33m 9s
Scala cross tests	33m 8s
Formatting	32s
Scalafix and docs	4m 51s
Sbt-metals/scripted jdk11	2m 40s
sbt-metals/scripted (Sbt 2)	1m 38s
Scala javapc tests	1m 24s
Scala 2.11 cross tests	4m 31s
MiMa	47s
	6h 58m 29s

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