Maintenance: Update dependency twilio-ruby to v7

Gemfile.lock

@@ -647,7 +647,7 @@ GEM
       bindata (~> 2.4)
       openssl (> 2.0)
       openssl-signature_algorithm (~> 1.0)
-    twilio-ruby (6.12.1)
+    twilio-ruby (7.0.0)
       faraday (>= 0.9, < 3.0)
       jwt (>= 1.5, < 3.0)
       nokogiri (>= 1.6, < 2.0)