Don't skip .so files

[nikitastupin]

https://github.com/ndelphit/apkurlgrep/blob/a188a980171450fdbd0a82f16a5a6963ac359587/extractor/skipExtensions.go#L28

.so files contains native code which may contain URLs too. I suggest to search URLs in them too.

You may process .so file with strings first.