Add test for len1_array_to_scalar function

Moved len1_array_to_scalar from a nested function to a staticmethod
of TFLiteSubgraph.

Change-Id: I182f0b70f03070855c1a4478d26644892c1ebb15
Signed-off-by: Diego Russo <diego.russo@arm.com>
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 704c15d..8b930b7 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -31,7 +31,7 @@
 
     -   id: pytest-cov
         name: pytest
-        stages: [commit]
+        stages: [push]
         language: system
         entry: pytest -v --cov=ethosu --cov-fail-under=0
         types: [python]