third_party/emboss: Update Python runner to be 3.11 compliant

"importlib.util" no longer transitively imports `importlib.machinery`
in 3.11.

Change-Id: Ie30d77b538867539be65838913098c1ab8e91a8f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/150235
Reviewed-by: Rob Mohr <mohrr@google.com>
Commit-Queue: Kevin Cho <chok@google.com>

third_party/emboss/embossc_runner.py

@@ -13,6 +13,7 @@
 # the License.
 
 import sys
+import importlib.machinery
 import importlib.util
 
 loader = importlib.machinery.SourceFileLoader("embossc", sys.argv[1])