Update pipelinewise-singer-python requirement from ==1.* to >=1,<3

Updates the requirements on [pipelinewise-singer-python](https://github.com/transferwise/pipelinewise-singer-python) to permit the latest version.
- [Release notes](https://github.com/transferwise/pipelinewise-singer-python/releases)
- [Changelog](https://github.com/transferwise/pipelinewise-singer-python/blob/master/CHANGELOG.md)
- [Commits](transferwise/pipelinewise-singer-python@v1.0.0...v2.0.1)

---
updated-dependencies:
- dependency-name: pipelinewise-singer-python
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

setup.py

@@ -18,7 +18,7 @@
       ],
       py_modules=['tap_slack'],
       install_requires=[
-          'pipelinewise-singer-python==1.*',
+          'pipelinewise-singer-python>=1,<3',
           'slack-sdk==3.20.0',
       ],
       extras_require={