MLBEDSW-3367 Update pre-commit flake8 version

Update the version of flake8 used in pre-commit to facilitate
adding mypy to pre-commit.

Signed-off-by: Jonas Ohlsson <jonas.ohlsson@arm.com>
Change-Id: I457dec87b77487ca6f14ff4a679c4cc927b272b0
diff --git a/ethosu/vela/tosa_reader.py b/ethosu/vela/tosa_reader.py
index aadcb0a..2bec9cf 100644
--- a/ethosu/vela/tosa_reader.py
+++ b/ethosu/vela/tosa_reader.py
@@ -253,7 +253,7 @@
         if tens.quantization.zero_point is None:
             tens.quantization.zero_point = zp
         elif tens.quantization.zero_point != zp:
-            print(f"Error: Setting tensor zp not possible, tensor already has different zero point")
+            print("Error: Setting tensor zp not possible, tensor already has different zero point")
             assert False