Disable tf-nightly from 2021-06-19, which lacks a linux build for pyt…

…hon 3.7, in tests

PiperOrigin-RevId: 380370181

testing/install_test_dependencies.sh

@@ -94,8 +94,7 @@ find_good_tf_nightly_version_str() {
   PKG_NAME=$1
   # These are nightly builds we'd like to avoid for some reason; separated by
   # regex OR operator.
-  BAD_NIGHTLY_DATES="20200112\|20200113\|20210119\|20210219\|20210220\|\
-  20210221\|20210222\|20210224\|20210316\|20210518\|20210519\|20210604"
+  BAD_NIGHTLY_DATES="20210519\|20210619"
   # This will fail to find version 'X" and log available version strings to
   # stderr. We then sort, remove bad versions and take the last entry. This
   # allows us to avoid hardcoding the main version number, which would then need