One possibility is to copy all the extjs files into the project folder and remove the gpl dependencies from the pom.xml.
Or you could create a bunch of libraries like I did with the gpl version and host them in your own maven repository. I wrote a simple helper application that splits the extjs distribution into different webjar libraries.
First you have to change the <distributionManagement> part in the template
resources-gen\src\main\resources\pom.mustache.
Check the config file extjs421.yaml. sourcedir has to point to the directory where extjs is located.
Then start the program on the command line like this:
java -jar target\resources-gen-0.0.1.jar extjs421.yaml
and it generates the libraries in the folder res.
After that you can simply deploy (mvn deploy) every library into your own maven repository.