use numpy 1.19.4 for python 3.9 builds

Author: jswhit

.travis.yml

@@ -78,14 +78,14 @@ matrix:
     - os: linux
       env:
         - MB_PYTHON_VERSION=3.9
-        - NP_BUILD_DEP="1.17.3"
-        - NP_TEST_DEP="1.17.3"
+        - NP_BUILD_DEP="1.19.4"
+        - NP_TEST_DEP="1.19.4"
     - os: linux
       env:
         - MB_PYTHON_VERSION=3.9
         - PLAT=i686
-        - NP_BUILD_DEP="1.17.3"
-        - NP_TEST_DEP="1.17.3"
+        - NP_BUILD_DEP="1.19.4"
+        - NP_TEST_DEP="1.19.4"
     #- os: osx
     #  language: generic
     #  env:
@@ -118,8 +118,8 @@ matrix:
       env:
         - MB_PYTHON_VERSION=3.9
         - MB_PYTHON_OSX_VER=10.9
-        - NP_BUILD_DEP="1.17.3"
-        - NP_TEST_DEP="1.17.3"
+        - NP_BUILD_DEP="1.19.4"
+        - NP_TEST_DEP="1.19.4"
 
 before_install:
     - BUILD_DEPENDS="numpy==$NP_BUILD_DEP Cython setuptools>=18.0"