MLBEDSW-6825: Restrict NumPy version limit to 1.21.3

There is an issue with using NumPy 1.21.4 or above in setup.py with
python 3.7. Restriction can most likely be removed when upgrading to
python 3.8.

Signed-off-by: Rickard Bolin <rickard.bolin@arm.com>
Change-Id: I9f826201d68bb5ab61f5bf76c7796442d34447b9
diff --git a/setup.py b/setup.py
index 42991c2..bf64535 100644
--- a/setup.py
+++ b/setup.py
@@ -94,11 +94,11 @@
     python_requires="~=3.7",
     install_requires=[
         "flatbuffers==1.12.0",
-        "numpy<=1.21.6",
+        "numpy<=1.21.3",
         "lxml>=4.5.1",
     ],
     entry_points={"console_scripts": ["vela = ethosu.vela.vela:main"]},
     ext_modules=[mlw_module],
     cmdclass={"build_ext": BuildExtension},  # type: ignore[dict-item]
-    setup_requires=["numpy<=1.21.6", "setuptools_scm"],
+    setup_requires=["numpy<=1.21.3", "setuptools_scm"],
 )