Fix failed VIES calls since Oct 28th 2021

[berislavbabic]

VIES calls started failing with this gem around October 28th. We traced
the issue back to the SOAPAction key being included in the request
header. Here is a quick fix to exclude the offending header.

For search purposes, the error we got was:
"Unknown error: (soap:Server) The given SOAPAction checkVat does not match an operation."

Before this fix:

>> VatCheck.new('LU20260743')
=> #<VatCheck:0x00007f8b98a09828 @vat="LU20260743", @regex=true, @response={:error=>"Unknown error: (soap:Server) The given SOAPAction checkVat does not match an operation."}, @vies_available=false, @vies=false>

After the fix:

>> VatCheck.new('LU20260743')
=> #<VatCheck:0x00007fc6fdabeca0 @vat="LU20260743", @regex=true, @response={:country_code=>"LU", :vat_number=>"20260743", :request_date=>Mon, 01 Nov 2021, :valid=>true, :name=>"AMAZON EU SARL", :address=>"38, AVENUE JOHN F. KENNEDY\nL-1855  LUXEMBOURG"}, @vies_available=true, @vies=true>

[thomasvbeek]

Looking good from our end, would be great if someone could merge this :)

[thomasvbeek]

@fastdivision Could we merge this? Looks good from our end and would fix the error that makes the gem unusable now :)

[mvz]

@fastdivision I'd really like to have this in a new release. Is there anything I can do to help move this forward?

[CLAassistant]

All committers have signed the CLA.

[mvz]

@berislavbabic any chance you could sign that CLA so @fastdivision or someone else at TaxJar can merge this?

[berislavbabic]

@mvz sorry I missed this notification. It's now signed

[mvz]

Thanks, @berislavbabic!

[berislavbabic]

@fastdivision can we get this merged please?