fix 'validate' imports for new package structure

src/configobj/__init__.py

@@ -2174,7 +2174,7 @@ def validate(self, validator, preserve_errors=False, copy=False,
             if preserve_errors:
                 # We do this once to remove a top level dependency on the validate module
                 # Which makes importing configobj faster
-                from validate import VdtMissingValue
+                from configobj.validate import VdtMissingValue
                 self._vdtMissingValue = VdtMissingValue
 
             section = self

src/tests/conftest.py

@@ -2,7 +2,7 @@
 import pytest
 
 from configobj import ConfigObj
-from validate import Validator
+from configobj.validate import Validator
 
 @pytest.fixture
 def empty_cfg():

src/tests/test_configobj.py

@@ -15,7 +15,7 @@
 
 import configobj as co
 from configobj import ConfigObj, flatten_errors, ReloadError, DuplicateError, MissingInterpolationOption, InterpolationLoopError, ConfigObjError
-from validate import Validator, VdtValueTooSmallError
+from configobj.validate import Validator, VdtValueTooSmallError
 
 
 def cfg_lines(config_string_representation):

src/tests/test_validate.py

@@ -5,7 +5,7 @@
 
 from configobj import ConfigObj
 import pytest
-from validate import Validator, VdtValueTooSmallError
+from configobj.validate import Validator, VdtValueTooSmallError
 
 
 class TestBasic(object):

src/tests/test_validate_errors.py

@@ -7,7 +7,7 @@
 import pytest
 
 from configobj import ConfigObj, get_extra_values, ParseError, NestingError
-from validate import Validator
+from configobj.validate import Validator
 
 @pytest.fixture()
 def thisdir():