tests: allow prerelease deps on Python 3.9 (#415)

tseaver · web-flow · commit 2bfb2cfc8a95 · 2021-08-11T22:16:28.000-04:00
Closes #414.
diff --git a/packages/google-cloud-firestore/testing/constraints-3.9.txt b/packages/google-cloud-firestore/testing/constraints-3.9.txt
@@ -0,0 +1,2 @@
+# Allow prerelease requirements
+--pre

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+# Allow prerelease requirements`
	`2`	`+--pre`