Update compat matrix table

Author: slinkydeveloper

README.md

@@ -121,10 +121,11 @@ The Rust SDK is currently in active development, and might break across releases
 
 The compatibility with Restate is described in the following table:
 
-| Restate Server\sdk-rust | 0.0/0.1/0.2 | 0.3 |
-|-------------------------|-------------|-----|
-| 1.0                     | ✅           | ❌   |
-| 1.1                     | ✅           | ✅   |
+| Restate Server\sdk-rust | 0.0/0.1/0.2 | 0.3 | 0.4 |
+|-------------------------|-------------|-----|-----|
+| 1.0                     | ✅           | ❌   | ❌   |
+| 1.1                     | ✅           | ✅   | ❌   |
+| 1.2                     | ✅           | ✅   | ✅   |
 
 ## Contributing