Revert "Fix missing f-string (#4150)"

This reverts commit 0590b3c37f136a9bdae9922299112b736302ac40.

Error when running test:

```
  File "/usr/local/google/home/laurenzo/src/iree-build/bindings/python/pyiree/rt/system_api.py", line 88, in _create_default_iree_driver
    print(f"Created IREE driver {driver_name}: {driver:!r}", file=sys.stderr)
TypeError: unsupported format string passed to pyiree.rt.binding.HalDriver.__format__
```
diff --git a/bindings/python/pyiree/rt/system_api.py b/bindings/python/pyiree/rt/system_api.py
index cfdce24..427e318 100644
--- a/bindings/python/pyiree/rt/system_api.py
+++ b/bindings/python/pyiree/rt/system_api.py
@@ -85,7 +85,7 @@
       driver_exceptions[driver_name] = ex
       continue
 
-    print(f"Created IREE driver {driver_name}: {driver:!r}", file=sys.stderr)
+    print("Created IREE driver {driver_name}: {driver:!r}", file=sys.stderr)
     return driver
 
   # All failed.