Issues with Reportlab and PDF backend

[corranwebster]

ReportLab 3.6.10 seems to have made a change that is causing tests of the PDF backend to fail in a fairly fundamental way.

Typical test failure:

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ERROR: test_circle (kiva.tests.test_pdf_drawing.TestPDFDrawing)
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Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/kiva/tests/drawing_tester.py", line 73, in test_circle
    self.gc.stroke_path()
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/contextlib.py", line 120, in __exit__
    next(self.gen)
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/kiva/tests/test_pdf_drawing.py", line 56, in draw_and_check
    line = content.getData().splitlines()[-2]
AttributeError: 'EncodedStreamObject' object has no attribute 'getData'