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/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 17d3877..8e976b6 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -13,7 +13,7 @@
         args: [--line-length=120]
 
 -   repo: https://gitlab.com/pycqa/flake8
-    rev: 3.7.9
+    rev: 4.0.1
     hooks:
     -   id: flake8
         args: [--max-line-length=120, --extend-ignore=E203]
diff --git a/ethosu/vela/scheduler.py b/ethosu/vela/scheduler.py
index 6b08459..3ef0d7f 100644
--- a/ethosu/vela/scheduler.py
+++ b/ethosu/vela/scheduler.py
@@ -1099,7 +1099,7 @@
             )
             print(f"\t\tSRAM Used: {mem_usage} bytes")
 
-        print(f"\tCascades:")
+        print("\tCascades:")
         for i, cascade in enumerate(schedule.cascades.values()):
             print(f"\t\t{i}: {cascade.start} -> {cascade.end}, size: {cascade.mem_usage}")
 
diff --git a/ethosu/vela/softmax.py b/ethosu/vela/softmax.py
index 13ca319..711c1e0 100644
--- a/ethosu/vela/softmax.py
+++ b/ethosu/vela/softmax.py
@@ -501,9 +501,7 @@
         reciprocal_right_shift = add_op_get_ofm(create_sub(name, const_31, headroom_plus_one, no_scale_quant))
 
         # PASS 7 - SHL
-        one = create_const_tensor(
-            f"one_const", [1, 1, 1, 1], DataType.int32, [1], np.int32, quantization=no_scale_quant
-        )
+        one = create_const_tensor("one_const", [1, 1, 1, 1], DataType.int32, [1], np.int32, quantization=no_scale_quant)
         constant_one = add_op_get_ofm(
             create_shl(f"{self.op.name}_shl{pass_number}", one, reciprocal_right_shift, no_scale_quant)
         )
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