Fix typo in ninja.py: oterweise -> otherwise

Bug: N/A
Change-Id: I04e9a60ff2047ae8d77e2504505aef3cf22e6050
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4295213
Auto-Submit: Edman Anjos <edman@chromium.org>
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>

ninja.py

@@ -41,7 +41,7 @@ def fallback(ninja_args):
       'the current project, nor in your PATH.\n'
       'Please take a following action to install Ninja.\n'
       '- If your project has DEPS, Add a CIPD Ninja dependency to DEPS.\n'
-      '- Oterweise, Add Ninja to your PATH *after* depot_tools.',
+      '- Otherwise, add Ninja to your PATH *after* depot_tools.',
       file=sys.stderr)
   return 1