Update versioneer: 0.18 → 0.20

Fix LGTM.com error: Suspicious unused loop iteration variable
For loop variable 'i' is not used in the loop body.

.circleci/config.yml

@@ -25,9 +25,10 @@ jobs:
           name: test python
           command: |
             conda activate testenv
-            pytest --doctest-modules bids-validator/bids_validator
-            flake8 bids-validator/bids_validator
-            pydocstyle bids-validator/bids_validator/bids_validator.py
+            cd bids-validator
+            pytest --doctest-modules bids_validator
+            flake8 bids_validator
+            pydocstyle bids_validator/bids_validator.py
   test:
     docker:
       - image: node:12.16.1

.github/workflows/python_tests.yml

@@ -55,9 +55,10 @@ jobs:
       - name: Check formatting
         shell: bash -l {0}
         run: |
-          flake8 bids-validator/bids_validator
-          pydocstyle bids-validator/bids_validator/bids_validator.py
+          cd bids-validator
+          flake8 bids_validator
+          pydocstyle bids_validator/bids_validator.py
       - name: Test with pytest
         shell: bash -l {0}
         run: |
-          pytest --doctest-modules bids-validator/bids_validator --verbose
+          pytest --doctest-modules bids-validator/bids_validator --verbose --ignore versioneer.py,_version.py

bids-validator/bids_validator/__init__.py

@@ -1,6 +1,6 @@
 """BIDS validator common Python package."""
-from ._version import get_versions
 from .bids_validator import BIDSValidator
-__version__ = get_versions()['version']
 __all__ = ['BIDSValidator']
-del get_versions
+
+from . import _version
+__version__ = _version.get_versions()['version']