Add missing space in string

Signed-off-by: Werner Lewis <werner.lewis@arm.com>
diff --git a/scripts/mbedtls_dev/bignum_core.py b/scripts/mbedtls_dev/bignum_core.py
index b4dff89..a300225 100644
--- a/scripts/mbedtls_dev/bignum_core.py
+++ b/scripts/mbedtls_dev/bignum_core.py
@@ -387,7 +387,7 @@
             "DD15FE80B731872AC104DB37832F7E75A244AA2631BC87885B861E8F20375499",
             (
                 "0xDD15FE80B731872AC104DB37832F7E75A244AA2631BC87885B861E8F20375499"
-                "is (dec) 99999999977^7"
+                " is (dec) 99999999977^7"
             )
         ),
         (