create same contact-colors when addresses differ in upper-/lowercase (#3327)

* create same contact-colors when addresses differ in upper-/lowercase

this leaves group-colors based on group names as is,
so, "MY GROUP" creates a different color than "my group",
as these names are better synced and also not an ID in this sense,
this is probably fine here.
(also when looking at the examples from
https://xmpp.org/extensions/xep-0392.html#testvectors-fullrange-no-cvd ,
case-sensistifity for group names seems to be fine)

* add a test for upper-/lowercase in group names

* update CHANGELOG

src/chat.rs

@@ -4905,6 +4905,22 @@ mod tests {
         Ok(())
     }
 
+    #[async_std::test]
+    async fn test_chat_get_color() -> Result<()> {
+        let t = TestContext::new().await;
+        let chat_id = create_group_chat(&t, ProtectionStatus::Unprotected, "a chat").await?;
+        let color1 = Chat::load_from_db(&t, chat_id).await?.get_color(&t).await?;
+        assert_eq!(color1, 0x008772);
+
+        // upper-/lowercase makes a difference for the colors, these are different groups
+        // (in contrast to email addresses, where upper-/lowercase is ignored in practise)
+        let t = TestContext::new().await;
+        let chat_id = create_group_chat(&t, ProtectionStatus::Unprotected, "A CHAT").await?;
+        let color2 = Chat::load_from_db(&t, chat_id).await?.get_color(&t).await?;
+        assert_ne!(color2, color1);
+        Ok(())
+    }
+
     async fn test_sticker(filename: &str, bytes: &[u8], w: i32, h: i32) -> Result<()> {
         let alice = TestContext::new_alice().await;
         let bob = TestContext::new_bob().await;