FIX: Bring back Azure support. (#407)

We thought Azure's latest API version didn't have tool support yet, but I didn't understand it was complaining about a required field in the tool call message.

lib/completions/dialects/chat_gpt.rb

@@ -75,6 +75,7 @@ module DiscourseAi
 
               {
                 role: "assistant",
+                content: nil,
                 tool_calls: [{ type: "function", function: function, id: context[:name] }],
               }
             else

spec/lib/completions/dialects/chat_gpt_spec.rb

@@ -85,6 +85,11 @@ RSpec.describe DiscourseAi::Completions::Dialects::ChatGpt do
         { type: "user", name: "user1", content: "This is a new message by a user" },
         { type: "assistant", content: "I'm a previous bot reply, that's why there's no user" },
         { type: "tool", name: "tool_id", content: "I'm a tool result" },
+        {
+          type: "tool_call",
+          name: "tool_id",
+          content: { name: "get_weather", arguments: { location: "Sydney", unit: "c" } }.to_json,
+        },
       ]
     end
 
@@ -95,7 +100,21 @@ RSpec.describe DiscourseAi::Completions::Dialects::ChatGpt do
 
       expect(translated_context).to eq(
         [
-          { role: "tool", content: context.last[:content], tool_call_id: context.last[:name] },
+          {
+            role: "assistant",
+            content: nil,
+            tool_calls: [
+              {
+                type: "function",
+                function: {
+                  name: "get_weather",
+                  arguments: { location: "Sydney", unit: "c" }.to_json,
+                },
+                id: "tool_id",
+              },
+            ],
+          },
+          { role: "tool", content: context.third[:content], tool_call_id: context.third[:name] },
           { role: "assistant", content: context.second[:content] },
           { role: "user", content: context.first[:content], name: context.first[:name] },
         ],
@@ -103,13 +122,13 @@ RSpec.describe DiscourseAi::Completions::Dialects::ChatGpt do
     end
 
     it "trims content if it's getting too long" do
-      context.last[:content] = context.last[:content] * 1000
+      context.third[:content] = context.third[:content] * 1000
 
       prompt[:conversation_context] = context
 
       translated_context = dialect.conversation_context
 
-      expect(translated_context.last[:content].length).to be < context.last[:content].length
+      expect(translated_context.third[:content].length).to be < context.third[:content].length
     end
   end