Register error for readonly attribute

Author: namannimmo10

tests/errors/test_assign8.py

@@ -0,0 +1,6 @@
+def f():
+    c: c32
+    c = complex(3, 4)
+    c.real = 5.0
+
+f()

tests/reference/asr-test_assign8-4b26e63.json

@@ -0,0 +1,13 @@
+{
+    "basename": "asr-test_assign8-4b26e63",
+    "cmd": "lpython --show-asr --no-color {infile} -o {outfile}",
+    "infile": "tests/errors/test_assign8.py",
+    "infile_hash": "c88b84b8d7d21aec489288c9064cc9d5a46387b5e6528d30a947ff5c",
+    "outfile": null,
+    "outfile_hash": null,
+    "stdout": null,
+    "stdout_hash": null,
+    "stderr": "asr-test_assign8-4b26e63.stderr",
+    "stderr_hash": "d3f4498398b59be4a1f83de67135842aa5a9a0921e1aa188dc743ca8",
+    "returncode": 2
+}

tests/reference/asr-test_assign8-4b26e63.stderr

@@ -0,0 +1,5 @@
+semantic error: readonly attribute
+ --> tests/errors/test_assign8.py:4:5
+  |
+4 |     c.real = 5.0
+  |     ^^^^^^^^^^^^ 

tests/tests.toml

@@ -638,6 +638,10 @@ asr = true
 filename = "errors/test_assign7.py"
 asr = true
 
+[[test]]
+filename = "errors/test_assign8.py"
+asr = true
+
 [[test]]
 filename = "errors/test_binop1.py"
 asr = true