Add requirements.txt to pg_probackup2

Author: vshepard

testgres/plugins/pg_probackup2/pg_probackup2/tests/requrements.txt

@@ -0,0 +1,10 @@
+# Testgres can be installed in the following ways:
+# 1. From a pip package (recommended)
+#    testgres==1.8.5
+# 2. From a specific Git branch, tag or commit
+#    git+https://github.com/postgrespro/testgres.git@<git-ref>
+#	 git+https://github.com/postgrespro/testgres.git@master
+#	 git+https://github.com/postgrespro/testgres.git@master#egg=testgres-pg_probackup2&subdirectory=testgres/plugins/pg_probackup2
+# 3. From a local directory
+#    /path/to/local/directory/testgres
+testgres==1.10.5

testgres/plugins/pg_probackup2/pg_probackup2/tests/test_basic.py

@@ -4,7 +4,7 @@
 import shutil
 import pytest
 
-from ...... import testgres
+import testgres
 from ...pg_probackup2.app import ProbackupApp
 from ...pg_probackup2.init_helpers import Init, init_params
 from ..storage.fs_backup import FSTestBackupDir