Bump org.apache.maven.plugins:maven-gpg-plugin from 3.2.7 to 3.2.8 (#604)

Co-authored-by: Boni Garcia <boni.garcia@uc3m.es>

Author: dependabot[bot]

pom.xml

@@ -26,7 +26,7 @@
         <maven-release-plugin.version>3.1.1</maven-release-plugin.version>
         <maven-surefire-plugin.version>3.5.3</maven-surefire-plugin.version>
         <jacoco-maven-plugin.version>0.8.13</jacoco-maven-plugin.version>
-        <maven-gpg-plugin.version>3.2.7</maven-gpg-plugin.version>
+        <maven-gpg-plugin.version>3.2.8</maven-gpg-plugin.version>
         <exec-maven-plugin.version>3.0.0</exec-maven-plugin.version>
         <maven-asciidoctor-plugin.version>3.2.0</maven-asciidoctor-plugin.version>
         <asciidoctorj-pdf.version>2.3.19</asciidoctorj-pdf.version>