Bump plugin.spring from 1.6.10 to 1.6.20

Bumps plugin.spring from 1.6.10 to 1.6.20.

---
updated-dependencies:
- dependency-name: plugin.spring
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

build.gradle.kts

@@ -4,7 +4,7 @@ plugins {
     id("org.springframework.boot") version "2.6.6" apply false
     id("io.spring.dependency-management") version "1.0.11.RELEASE" apply false
     kotlin("jvm") version "1.6.10" apply false
-    kotlin("plugin.spring") version "1.6.10" apply false
+    kotlin("plugin.spring") version "1.6.20" apply false
     // kotlin("plugin.jpa") version "1.6.10" apply false
 }