BLD: bump to latest numpy in builds

Author: Gerry Manoim

.github/workflows/main.yml

@@ -25,9 +25,9 @@ jobs:
           - python-version: 3.5
             numpy: 1.11.3
           - python-version: 3.6
-            numpy: 1.18.1
+            numpy: 1.19
           - python-version: 3.8
-            numpy: 1.18.1
+            numpy: 1.19
     steps:
     - uses: actions/checkout@v2
       with:

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
         PYTHONWARNINGS: ignore:DEPRECATION::pip._internal.cli.base_command
       run: |
         python -m pip install --upgrade pip
-        pip install numpy==1.18.1
+        pip install numpy==1.19
     - name: Install c++ dependencies (ubuntu)
       run: |
         sudo apt-get -y install libsparsehash-dev doxygen