tests: revert testing against prerelease deps on Python 3.9 (#426)

Reverts #415 Consensus from today's meeting is that testing prereleases of third-party dependencies needs to happen outside the normal `presubmit` path.
googleapis · Aug 18, 2021 · cf9cddb · cf9cddb
1 parent b56fd28
commit cf9cddb
Showing 1 changed file with 0 additions and 2 deletions.
diff --git a/testing/constraints-3.9.txt b/testing/constraints-3.9.txt
@@ -1,2 +0,0 @@
-# Allow prerelease requirements
---pre