Build break in pydoc

[NikolajBjorner]

Fix these build error in the pyodide pipeline.
The fix is to replace the Expected string by the strings that were "Got".

Successfully installed z3-solver-4.15.3.0
WARNING: Location 'file:/home/runner/.cache/.pyodide-xbuildenv-0.30.5/0.27.7/xbuildenv/pyodide-root/package_index/pip/' is ignored: it is neither a file nor a directory.
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File "/home/runner/env-pyodide/lib/python3.12/site-packages/z3/z3.py", line 4251, in z3.z3.Extract
Failed example:
    Extract(s, 1, 3)  # Extract 3 characters starting at position 1
Expected:
    Extract(StringVal("hello"), 1, 3)
Got:
    str.substr("hello", 1, 3)
**********************************************************************
File "/home/runner/env-pyodide/lib/python3.12/site-packages/z3/z3.py", line 11231, in z3.z3.SubSeq
Failed example:
    SubSeq(s, 0, 5)  # Extract "hello"  
Expected:
    Extract(StringVal("hello world"), 0, 5)
Got:
    str.substr("hello world", 0, 5)
**********************************************************************
File "/home/runner/env-pyodide/lib/python3.12/site-packages/z3/z3.py", line 11217, in z3.z3.SubString
Failed example:
    SubString(s, 6, 5)  # Extract "world"
Expected:
    Extract(StringVal("hello world"), 6, 5)
Got:
    str.substr("hello world", 6, 5)
**********************************************************************
3 items had failures:
   1 of   9 in z3.z3.Extract
   1 of   3 in z3.z3.SubSeq
   1 of   3 in z3.z3.SubString