build(deps): bump dev.sigstore.sign from 1.1.0 to 1.2.0 in /java

Bumps dev.sigstore.sign from 1.1.0 to 1.2.0.

---
updated-dependencies:
- dependency-name: dev.sigstore.sign
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

java/build.gradle.kts

@@ -1,7 +1,7 @@
 plugins {
     `java-library`
     `maven-publish`
-    id("dev.sigstore.sign") version "1.1.0"
+    id("dev.sigstore.sign") version "1.2.0"
     id("com.diffplug.spotless") version "6.25.0"
     `signing`
 }