Remove --enable-dotnet argument while building yara-python in Appveyor.

This argument has been removed in #222

Author: plusvic

appveyor.yml

@@ -127,7 +127,7 @@ clone_script:
 
 build_script:
   # Build the compiled extension
-  - "%CMD_IN_ENV% python setup.py build_ext --enable-cuckoo --enable-dotnet
+  - "%CMD_IN_ENV% python setup.py build_ext --enable-cuckoo
     -L../jansson-%JANSSON_VERSION%/build/lib/Release;../openssl/lib
     -I../jansson-%JANSSON_VERSION%/build/include;../openssl/include
     -DHASH_MODULE,HAVE_LIBCRYPTO,BUCKETS_128,CHECKSUM_1B