fix: fix regex for filtering credentials from logs

The ending "=" character of a base64 encoded string is padding. When the
input length is a multiple of three (which is the case for our account
id and license key), the output would not have the padding character.
This results in our credentials not being filtered in the logs.

This fixes the regex by removing the incorrect assumption.

https://en.wikipedia.org/wiki/Base64#Output_padding

lib/avatax/connection.rb

@@ -4,7 +4,8 @@ module AvaTax
 
   module Connection
     private
-    AUTHORIZATION_FILTER_REGEX = /(Authorization\:\ \"Basic\ )(\w+)\=/
+
+    AUTHORIZATION_FILTER_REGEX = /(Authorization:\ "Basic\ )(\w+)/
     REMOVED_LABEL = '\1[REMOVED]'
 
     def connection

spec/avatax/request_spec.rb

@@ -1,4 +1,5 @@
 require File.expand_path('../../spec_helper', __FILE__)
+require 'logger'
 
 describe AvaTax::Request do
 
@@ -22,4 +23,22 @@
       expect(response.env.request['timeout']).to eq(10)
     end
   end
+
+  describe 'filter credentials from logs' do
+    let(:string_io) { StringIO.new }
+    let(:logger) { Logger.new(string_io) }
+
+    it 'replaces credentials with a label' do
+      # Make 'name:pass' string length a multiple of three so the base64
+      # encoded string will not have padding characters '=' at the end.
+      @client.username = 'name'
+      @client.password = 'pass'
+
+      @client.custom_logger = logger
+      response = @client.request(:get, 'path', 'model')
+
+      expect(response.env.request_headers).to include('Authorization' => 'Basic bmFtZTpwYXNz')
+      expect(string_io.string).to match(/Authorization: "Basic \[REMOVED\]"/)
+    end
+  end
 end