MLBEDSW-8111: Update to TensorFlow 2.14

- Update to TensorFlow 2.14 and minimum required Python version to 3.9.
- Update version pins on NumPy and FlatBuffers.
- Add constraint to Offset attribute of StridedSlice operator

Change-Id: I8c7122def963202e5f47e92b62be607935ed05cf
Signed-off-by: Rickard Bolin <rickard.bolin@arm.com>
diff --git a/pyproject.toml b/pyproject.toml
index fd4fc2d..8faa752 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,7 +17,7 @@
 [project]
 name = "ethos-u-vela"
 description = "Neural network model compiler for Arm Ethos-U NPUs"
-requires-python = "~=3.8"
+requires-python = "~=3.9"
 authors = [{name = "Arm Ltd", email = "mlg-vela@arm.com"}]
 license = {text= "Apache License 2.0"}
 classifiers = [
@@ -34,9 +34,8 @@
 ]
 keywords = ["ethos-u", "vela compiler", "tflite", "npu"]
 dependencies = [
-    "flatbuffers==23.1.21",
-    "numpy<=1.21.3; python_version<='3.7'",
-    "numpy; python_version>'3.7'",
+    "flatbuffers==23.5.26",
+    "numpy",
     "lxml>=4.5.2"
 ]
 dynamic = ["readme", "version"]
@@ -58,8 +57,7 @@
 
 [build-system]
 requires = [
-    "numpy<=1.21.3; python_version<='3.7'",
-    "numpy; python_version>'3.7'",
+    "numpy",
     "setuptools_scm[toml]~=7.1.0"
 ]
 build-backend = "setuptools.build_meta"