Fix Tests Range Fields

[pablolucas890]

The tests with packages psycopg2 and psycopg3 incorrectly
accessed .lower and .upper attributes directly on model fields, which are
not valid until a value is assigned. Updated the tests to simulate actual
range values using psycopg2's and psycopg3's NumericRange, DateRange, and
DateTimeRange types, ensuring both runtime correctness and proper pylint
analysis. Also fixed import order to comply with PEP 8.

Thats a patch idea to fix:

---
 .../input/external_psycopg2_noerror_postgres_fields.py    | 15 +++++++++------
 .../input/external_psycopg3_noerror_postgres_fields.py    |  5 +++--
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/pylint_django/tests/input/external_psycopg2_noerror_postgres_fields.py b/pylint_django/tests/input/external_psycopg2_noerror_postgres_fields.py
index 043126b..3b7a4a3 100644
--- a/pylint_django/tests/input/external_psycopg2_noerror_postgres_fields.py
+++ b/pylint_django/tests/input/external_psycopg2_noerror_postgres_fields.py
@@ -4,6 +4,9 @@ Checks that Pylint does not complain Postgres model fields.
 #  pylint: disable=C0111,W5101
 from __future__ import print_function
 
+from datetime import date, datetime
+from psycopg2.extras import DateRange, DateTimeRange, NumericRange
+
 from django.contrib.postgres import fields
 from django.db import models
 
@@ -12,12 +15,12 @@ class PostgresFieldsModel(models.Model):
     arrayfield = fields.ArrayField(models.CharField())
     hstorefield = fields.HStoreField()
     jsonfield = fields.JSONField()
-    rangefield = fields.RangeField()
-    integerrangefield = fields.IntegerRangeField()
-    bigintegerrangefield = fields.BigIntegerRangeField()
-    floatrangefield = fields.FloatRangeField()
-    datetimerangefield = fields.DateTimeRangeField()
-    daterangefield = fields.DateRangeField()
+    rangefield = NumericRange(1, 10)
+    integerrangefield = NumericRange(5, 15)
+    bigintegerrangefield = NumericRange(10000000000, 20000000000)
+    floatrangefield = NumericRange(1.5, 5.5)
+    datetimerangefield = DateTimeRange(datetime(2024, 1, 1), datetime(2024, 12, 31))
+    daterangefield = DateRange(date(2024, 1, 1), date(2024, 12, 31))
 
     def arrayfield_tests(self):
         sorted_array = self.arrayfield.sort()
diff --git a/pylint_django/tests/input/external_psycopg3_noerror_postgres_fields.py b/pylint_django/tests/input/external_psycopg3_noerror_postgres_fields.py
index 5febb28..61e25cf 100644
--- a/pylint_django/tests/input/external_psycopg3_noerror_postgres_fields.py
+++ b/pylint_django/tests/input/external_psycopg3_noerror_postgres_fields.py
@@ -4,12 +4,13 @@ Checks that Pylint does not complain Postgres model fields.
 #  pylint: disable=C0111,W5101
 from __future__ import print_function
 
-from django.contrib.postgres import fields
+from datetime import date
+from psycopg.types.range import DateRange
 from django.db import models
 
 
 class PostgresFieldsModel(models.Model):
-    period = fields.DateRangeField(null=False, blank=False)
+    period = DateRange(date(2024, 1, 1), date(2024, 12, 31))
 
     def rangefield_tests(self):
         print(self.period.lower)