update travisCI workflow for numpy version handling

Author: mpenkov

.travis.yml

@@ -20,13 +20,6 @@ env:
       - MB_ML_VER=2014
       - SKIP_NETWORK_TESTS=1
       - DOCKER_TEST_IMAGE=multibuild/xenial_arm64v8
-        #
-        # Build wheels with the oldest possible numpy version to avoid
-        # the problem encountered by:
-        #
-        # https://github.com/RaRe-Technologies/gensim/issues/3085
-        #
-      - BUILD_DEPENDS="oldest-supported-numpy scipy==1.7.0"
         #
         # The contents of this file mirror the linux_testenv list
         # in gensim's setup.py.  I can't think of a better way to include
@@ -36,23 +29,35 @@ env:
       - TEST_DEPENDS="pytest mock cython nmslib pyemd testfixtures Morfessor==2.0.2a4 python-levenshtein==0.12.0 visdom==0.1.8.9 scikit-learn"
 
 matrix:
+      #
+      # See .github/workflows/build-wheels.yml for a discussion of why we
+      # handle numpy versions explicitly.
+      #
     - os: linux
       env:
         - MB_PYTHON_VERSION=3.6
         #
         # scipy 1.7.0 wheels not available for Py3.6, so we have to build using
         # an older version.
         #
-        - BUILD_DEPENDS="oldest-supported-numpy scipy==1.5.3"
+        - BUILD_DEPENDS="numpy==1.19.2 scipy==1.5.3"
     - os: linux
       env:
         - MB_PYTHON_VERSION=3.7
+        - BUILD_DEPENDS="numpy==1.19.2 scipy==1.7.0"
     - os: linux
       env:
         - MB_PYTHON_VERSION=3.8
+        - BUILD_DEPENDS="numpy==1.19.2 scipy==1.7.0"
     - os: linux
       env:
         - MB_PYTHON_VERSION=3.9
+        #
+        # oldest-supported-numpy does not seem to handle this particular case
+        # (aarch64, Py3.9) explicitly, but I've double-checked that wheels for
+        # this numpy release are available via PyPI.
+        #
+        - BUILD_DEPENDS="numpy==1.19.3 scipy==1.7.0"
 
 before_install:
     - source multibuild/common_utils.sh