feature: add Union#allFloatLiterals as it was missing

Signed-off-by: Maximilian Bösing <2189546+boesing@users.noreply.github.com>

src/Psalm/Type/Union.php

@@ -1267,6 +1267,17 @@ final class Union implements TypeNode
         return true;
     }
 
+    public function allFloatLiterals(): bool
+    {
+        foreach ($this->types as $atomic_key_type) {
+            if (!$atomic_key_type instanceof TLiteralFloat) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     public function allLiterals(): bool
     {
         foreach ($this->types as $atomic_key_type) {