Revert "add back jdk version to MANIFEST.MF"

This reverts commit d186a913f35187c47e405ac23af053e59a0d09d7.
diff --git a/osgi.bnd b/osgi.bnd
index ceeed25..cac520e 100644
--- a/osgi.bnd
+++ b/osgi.bnd
@@ -54,6 +54,7 @@
 # for reproducible build (see https://bnd.bndtools.org/instructions/reproducible.html 
 # and https://bnd.bndtools.org/instructions/noextraheaders.html)
 -reproducible: true
+-noextraheaders: true
 
 # Non-OSGi meta:
 Main-Class: freemarker.core.CommandLine