[Backport 2.x] bump com.diffplug.spotless to 6.21.0 and com.github.wn…

…ameless.json:json-base to 2.4.2 (#3327)

Manual backports of
#3295 and
#3293 to 2.x

Signed-off-by: Craig Perkins <cwperx@amazon.com>

build.gradle

@@ -496,7 +496,7 @@ dependencies {
     implementation "io.jsonwebtoken:jjwt-impl:${jjwt_version}"
     implementation "io.jsonwebtoken:jjwt-jackson:${jjwt_version}"
     // JSON flattener
-    implementation ("com.github.wnameless.json:json-base:2.4.1") {
+    implementation ("com.github.wnameless.json:json-base:2.4.2") {
         exclude group: "org.glassfish", module: "jakarta.json"
         exclude group: "com.google.code.gson", module: "gson"
         exclude group: "org.json", module: "json"