remove python 3.9 from build-wheels.sh because OpenCV doesn't have version compatible with 3.5 too

README.rst

@@ -65,7 +65,7 @@ Changelog
 +----------------+------------+--------------------------------------------------------------------------------------------------------------------------------------+
 | Version        | Date       | Notes                                                                                                                                |
 +================+============+======================================================================================================================================+
-| Version 0.5.2.1| 2020-07-20 |  This is the version in the JOSS paper. Making python 3.8 and 3.9  package for PyPI, along with classifiers. Python 2.7 dropped      |
+| Version 0.5.2.1| 2020-07-20 |  This is the version in the JOSS paper. Making python 3.8 package for PyPI, along with classifiers. Python 2.7 dropped               |
 +----------------+------------+--------------------------------------------------------------------------------------------------------------------------------------+
 | Version 0.5.2  | 2020-06-03 |  Big improvements in spam-mmr and spam-mmr-graphical, all TSVs im1->im2 and gradients always computed in im2                         |
 +----------------+------------+--------------------------------------------------------------------------------------------------------------------------------------+

build-wheels.sh

@@ -8,7 +8,7 @@ PYBINS=(
    "/opt/python/cp36-cp36m/bin"
    "/opt/python/cp37-cp37m/bin"
    "/opt/python/cp38-cp38/bin"
-   "/opt/python/cp39-cp39/bin"
+#   "/opt/python/cp39-cp39/bin"
   )
 
 # Compile wheels