Fix syntax error in retry middleware

Replace retry statements with loop/next pattern to avoid
'Invalid retry without rescue' syntax error in Ruby

Author: vipulnsward

lib/uploadcare/middleware/retry.rb

@@ -23,25 +23,27 @@ def initialize(app, options = {})
 
       def call(env)
         retries = 0
-        begin
-          response = @app.call(env)
-
-          if should_retry?(env, response, nil, retries)
-            retries += 1
-            log_retry(env, response[:status], retries, "status code #{response[:status]}")
-            sleep(calculate_delay(retries, response))
-            retry
+        loop do
+          begin
+            response = @app.call(env)
+
+            if should_retry?(env, response, nil, retries)
+              retries += 1
+              log_retry(env, response[:status], retries, "status code #{response[:status]}")
+              sleep(calculate_delay(retries, response))
+              next
+            end
+
+            return response
+          rescue StandardError => e
+            if should_retry?(env, nil, e, retries)
+              retries += 1
+              log_retry(env, nil, retries, e.class.name)
+              sleep(calculate_delay(retries))
+              next
+            end
+            raise
           end
-
-          response
-        rescue StandardError => e
-          if should_retry?(env, nil, e, retries)
-            retries += 1
-            log_retry(env, nil, retries, e.class.name)
-            sleep(calculate_delay(retries))
-            retry
-          end
-          raise
         end
       end