Fix missing import in tests

crates/nu-std/testing.nu

@@ -287,6 +287,8 @@ export def run-tests [
     --list,                               # list the selected tests without running them.
     --threads: int@"nu-complete threads", # Amount of threads to use for parallel execution. Default: All threads are utilized
 ] {
+    use std log
+
     let available_threads = (sys cpu | length)
 
     # Can't use pattern matching here due to https://github.com/nushell/nushell/issues/9198