Update to conda recipe for Python 3.9 (#105)

Author: cmccarthy1

conda-recipe/conda_build_config.yaml

@@ -3,3 +3,4 @@ python:
   - 3.6
   - 3.7
   - 3.8
+  - 3.9

conda-recipe/prep_requirements.q

@@ -1,6 +1,6 @@
 / exclude packages from tests/requirements.txt based on python major minor version
 \l p.q
-pexclude:select py37:enlist"tensorflow*",py38:enlist"tensorflow*"  from (0#`)!()
+pexclude:select py37:enlist"tensorflow*",py38:enlist"tensorflow*",py39:enlist"tensorflow"  from (0#`)!()
 pver:`$"py",raze string .p.import[`sys;`:version_info][;`]each`:major`:minor
 `:tests/requirements_filtered.txt 0:u where not any(u:read0`:tests/requirements.txt)like/:pexclude pver
 \\