Change default stacklevel for deprecation warning

[jenshnielsen]

Level 2 is inside decorate_callable e.g. one level up from the warning
Level 3 is the call that actually triggers the warning
e.g. two levels up from the warning

For example if I were to deprecate dataset.parameters and run the test suite
the warnings before would be.

qcodes/tests/dataset/test_dataset_basic.py: 3 warnings
qcodes/tests/dataset/test_database_extract_runs.py: 22 warnings
qcodes/tests/dataset/test_database_creation_and_upgrading.py: 2 warnings
qcodes/tests/dataset/test_dataset_loading.py: 2 warnings
qcodes/tests/dataset/test_doNd.py: 7 warnings
qcodes/tests/dataset/measurement/test_measurement_context_manager.py: 24 warnings
  C:\Users\jenielse\source\repos\Qcodes\qcodes\utils\deprecate.py:59: QCoDeSDeprecationWarning: The function <parameters> is deprecated. Use "dataset.rundescriber.parameters" as an alternative.
    issue_deprecation_warning(f'{t} <{n}>', reason, alternative)

With this fix its

qcodes/tests/dataset/test_dataset_basic.py::test_has_attributes_after_init
  C:\Users\jenielse\source\repos\Qcodes\qcodes\tests\dataset\test_dataset_basic.py:68: QCoDeSDeprecationWarning: The function <parameters> is deprecated. Use "dataset.rundescriber.parameters" as an alternative.
    assert hasattr(ds, attr)

qcodes/tests/dataset/test_dataset_basic.py::test_has_attributes_after_init
  C:\Users\jenielse\source\repos\Qcodes\qcodes\tests\dataset\test_dataset_basic.py:69: QCoDeSDeprecationWarning: The function <parameters> is deprecated. Use "dataset.rundescriber.parameters" as an alternative.
    getattr(ds, attr)

qcodes/tests/dataset/test_dataset_basic.py::test_has_attributes_after_init
  C:\Users\jenielse\source\repos\Qcodes\qcodes\tests\dataset\test_dataset_basic.py:74: QCoDeSDeprecationWarning: The function <parameters> is deprecated. Use "dataset.rundescriber.parameters" as an alternative.
    assert hasattr(ds, attr)

qcodes/tests/dataset/test_dataset_basic.py::test_has_attributes_after_init
  C:\Users\jenielse\source\repos\Qcodes\qcodes\tests\dataset\test_dataset_basic.py:75: QCoDeSDeprecationWarning: The function <parameters> is deprecated. Use "dataset.rundescriber.parameters" as an alternative.
    getattr(ds, attr)

qcodes/tests/dataset/test_dataset_basic.py::test_the_same_dataset_as
  C:\Users\jenielse\source\repos\Qcodes\qcodes\dataset\data_set_protocol.py:318: QCoDeSDeprecationWarning: The function <parameters> is deprecated. Use "dataset.rundescriber.parameters" as an alternative.
    if getattr(self, attr) != getattr(other, attr):

qcodes/tests/dataset/test_dataset_basic.py::test_empty_ds_parameters
  C:\Users\jenielse\source\repos\Qcodes\qcodes\tests\dataset\test_dataset_basic.py:1284: QCoDeSDeprecationWarning: The function <parameters> is deprecated. Use "dataset.rundescriber.parameters" as an alternative.
    assert ds.parameters is None

qcodes/tests/dataset/test_dataset_basic.py::test_empty_ds_parameters
  C:\Users\jenielse\source\repos\Qcodes\qcodes\tests\dataset\test_dataset_basic.py:1286: QCoDeSDeprecationWarning: The function <parameters> is deprecated. Use "dataset.rundescriber.parameters" as an alternative.
    assert ds.parameters is None

qcodes/tests/dataset/test_dataset_basic.py::test_empty_ds_parameters
  C:\Users\jenielse\source\repos\Qcodes\qcodes\tests\dataset\test_dataset_basic.py:1288: QCoDeSDeprecationWarning: The function <parameters> is deprecated. Use "dataset.rundescriber.parameters" as an alternative.
    assert ds.parameters is None

....

[jenshnielsen]

Should probably add a news fragment

[codecov]

Codecov Report

Merging #3959 (8c36806) into master (ef0d31b) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #3959   +/-   ##
=======================================
  Coverage   65.83%   65.83%           
=======================================
  Files         228      228           
  Lines       31464    31464           
=======================================
  Hits        20714    20714           
  Misses      10750    10750