Update build constraints for use within project constraints (#27)

Author: adrianeboyd

build-constraints.txt

@@ -1,8 +1,4 @@
 # build version constraints for use with wheelwright + multibuild
-numpy==1.15.0; python_version<='3.7' and platform_machine!='aarch64'
-numpy==1.19.2; python_version<='3.7' and platform_machine=='aarch64'
-numpy==1.17.3; python_version=='3.8' and platform_machine!='aarch64'
-numpy==1.19.2; python_version=='3.8' and platform_machine=='aarch64'
-numpy==1.19.3; python_version=='3.9'
+numpy==1.21.0; python_version<='3.9'
 numpy==1.21.3; python_version=='3.10'
 numpy; python_version>='3.11'