chore: revert maven-gpg-plugin 3.2.7

Motivation:

3.2.8 seems to be broken because of bouncycastle.

Author: slandelle

pom.xml

@@ -334,7 +334,7 @@
         </plugin>
         <plugin>
           <artifactId>maven-gpg-plugin</artifactId>
-          <version>3.2.8</version>
+          <version>3.2.7</version>
         </plugin>
         <plugin>
           <artifactId>maven-install-plugin</artifactId>