fix: subscription test case

Co-authored-by: Marica <maricadsouza221197@gmail.com>

Co-authored-by: rohitwaghchaure <rohitw1991@gmail.com>
Co-authored-by: Marica <maricadsouza221197@gmail.com>
diff --git a/erpnext/accounts/doctype/subscription/test_subscription.py b/erpnext/accounts/doctype/subscription/test_subscription.py
index 811fc35..c17fccd 100644
--- a/erpnext/accounts/doctype/subscription/test_subscription.py
+++ b/erpnext/accounts/doctype/subscription/test_subscription.py
@@ -237,7 +237,7 @@
 		subscription.party_type = 'Customer'
 		subscription.party = '_Test Customer'
 		subscription.append('plans', {'plan': '_Test Plan Name', 'qty': 1})
-		subscription.start_date = '2018-01-01'
+		subscription.start_date = add_days(nowdate(), -1000)
 		subscription.insert()
 		subscription.process()		# generate first invoice