Bump annotations from 20.1.0 to 21.0.1 in /core

Bumps [annotations](https://github.com/JetBrains/java-annotations) from 20.1.0 to 21.0.1.
- [Release notes](https://github.com/JetBrains/java-annotations/releases)
- [Changelog](https://github.com/JetBrains/java-annotations/blob/master/CHANGELOG.md)
- [Commits](JetBrains/java-annotations@20.1.0...21.0.1)

Signed-off-by: dependabot[bot] <support@github.com>

core/build.gradle

@@ -171,8 +171,8 @@ dependencies {
 
     compile 'junit:junit:4.12'
     compile 'org.slf4j:slf4j-api:1.7.30'
-    compileOnly 'org.jetbrains:annotations:20.1.0'
-    testCompileClasspath 'org.jetbrains:annotations:20.0.0'
+    compileOnly 'org.jetbrains:annotations:21.0.1'
+    testCompileClasspath 'org.jetbrains:annotations:21.0.1'
     compile 'org.apache.commons:commons-compress:1.20'
     compile ('org.rnorth.duct-tape:duct-tape:1.0.8') {
         exclude(group: 'org.jetbrains', module: 'annotations')