`RuntimeCollector` uses unsupported `tags` keyword when registering gauges

[thesmith]

When running the RuntimeCollector example I receive the following error:

  File "wavefront_pyformance/wavefront_reporter.py", line 187, in report_now
    super(WavefrontDirectReporter, self).report_now(registry, timestamp)
  File "wavefront_pyformance/wavefront_reporter.py", line 50, in report_now
    self._report(registry, timestamp, False)
  File "wavefront_pyformance/wavefront_reporter.py", line 66, in _report
    col.collect()
  File "wavefront_pyformance/runtime_metrics.py", line 129, in collect
    self.collect_cputimes()
  File "wavefront_pyformance/runtime_metrics.py", line 34, in collect_cputimes
    tags=self.custom_tags).set_value(cpu_u_mode)
TypeError: gauge() got an unexpected keyword argument 'tags'

I'm using pipenv and here is my pipenv graph output for the module:

wavefront-pyformance==1.1.0
  - psutil [required: >=5.6.3, installed: 5.8.0]
  - pyformance [required: >=0.4, installed: 0.4]
    - six [required: Any, installed: 1.15.0]
  - wavefront-sdk-python [required: >=1.1, installed: 1.7.4]
    - requests [required: >=2.18.4, installed: 2.25.1]
      - certifi [required: >=2017.4.17, installed: 2020.12.5]
      - chardet [required: >=3.0.2,<5, installed: 4.0.0]
      - idna [required: >=2.5,<3, installed: 2.10]
      - urllib3 [required: >=1.21.1,<1.27, installed: 1.25.11]
    - tdigest [required: >=0.5.2, installed: 0.5.2.2]
      - accumulation-tree [required: Any, installed: 0.6.2]
      - pyudorandom [required: Any, installed: 1.0.0]