_content/blog/testing-time.md: fix typo

Fixes golang/go#75263.

Change-Id: I5957951acf2588dacbdb59334d5606b6d49d16ea
Reviewed-on: https://go-review.googlesource.com/c/website/+/701055
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Sean Liao <[email protected]>
Auto-Submit: Dmitri Shuralyov <[email protected]>

Author: jba

_content/blog/testing-time.md

@@ -948,7 +948,7 @@ where a durably blocked goroutine can be unblocked from outside its bubble.
 ### Better stack traces
 
 We made improvements to the information printed in stack traces.
-When a bubble deadlocks, we by default now only print stacks for the goroutines in tha bubble.
+When a bubble deadlocks, we by default now only print stacks for the goroutines in that bubble.
 Stack traces also clearly indicate which goroutines in a bubble are durably blocked.
 
 ### Randomized events happening at the same time