Update required numpy.

HexDecimal · HexDecimal · commit 06e231c55f8f · 2021-05-30T15:25:25.000-07:00
This to resolve type checking.  The install required version is
unchanged.
diff --git a/requirements.txt b/requirements.txt
@@ -1,5 +1,5 @@
 cffi~=1.13
-numpy>=1.20.0rc1; python_version >= '3.7'
+numpy>=1.20.3; python_version >= '3.7'
 numpy>=1.19.5; python_version <= '3.6'
 pycparser>=2.14
 setuptools>=36.0.1
