feat: remove unused dependency from sigstore-gradle-sign-base-plugin

Signed-off-by: Vladimir Sitnikov <[email protected]>

Author: vlsi

sigstore-gradle/sigstore-gradle-sign-base-plugin/build.gradle.kts

@@ -7,7 +7,6 @@ description = "Gradle plugin with the base set of tasks and configurations for S
 
 dependencies {
     compileOnly(project(":sigstore-java"))
-    implementation("com.fasterxml.jackson.core:jackson-databind:2.14.2")
 
     sigstoreJavaRuntime(project(":sigstore-java")) {
         because("Test code needs access locally-built sigstore-java as a Maven repository")