SLING-7534 use newest ASF parent (21) to generate SHA512 checksums with
the release
diff --git a/pom.xml b/pom.xml
index 99ba021..d8cd5e5 100644
--- a/pom.xml
+++ b/pom.xml
@@ -21,7 +21,7 @@
     <parent>
         <groupId>org.apache</groupId>
         <artifactId>apache</artifactId>
-        <version>20</version>
+        <version>21</version>
         <relativePath />
     </parent>