exclude ahc.properties for license check
### Motivation
license-maven-plugin check fail for ahc.properties, maybe related with license-maven-plugin update in
![licenseCheck](https://user-images.githubusercontent.com/65590138/100595150-81dd9d80-3335-11eb-8539-3dd07f982442.PNG)
### Modifications
Add ahc.properties to exclude list of license-maven-plugin
@@ -1170,6 +1170,7 @@ flexible messaging model and an intuitive client API.</description>
<exclude>**/src/main/java/org/apache/bookkeeper/mledger/util/AbstractCASReferenceCounted.java</exclude>
<exclude>**/ByteBufCodedInputStream.java</exclude>
<exclude>**/ByteBufCodedOutputStream.java</exclude>
+ <exclude>**/ahc.properties</exclude>
<exclude>bin/proto/*</exclude>
<exclude>conf/schema_example.conf</exclude>
<exclude>data/**</exclude>
