[lldb][test] Remove Python <= 3.6 workaround (#215262)
re.Pattern was added in 3.7 and our minimum
is now 3.8.
Python 3.6.15:
>>> import re
>>> re.Pattern
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: module 're' has no attribute 'Pattern'
Python 3.7.17:
>>> import re
>>> re.Pattern
<class 're.Pattern'>
Python 3.8.20:
>>> import re
>>> re.Pattern
<class 're.Pattern'>
(it does not appear in documentation until 3.11)
