build(publish): 增加构件签名过程.

增加构件 GPG 签名, 可保证构件未被修改, 增加构件可信度.

scalabot-extension/build.gradle.kts

@@ -4,6 +4,7 @@ plugins {
     kotlin("jvm") version "1.6.10"
     java
     `maven-publish`
+    signing
 }
 
 dependencies {
@@ -94,3 +95,8 @@ publishing {
     }
 
 }
+
+signing {
+    useGpgCmd()
+    sign(publishing.publications["maven"])
+}