lang/spidermonkey91: fix build with Python 3.11

open(), io.open() et al no longer accept 'U' ("universal newline")
in the file mode; the flag had been deprecated since Python 3.3. [0]
Failed during configure.

While here, remove duplicate Python dependency line and use root
configure script.

References:
[0] https://docs.python.org/3/whatsnew/3.11.html#porting-to-python-3-11

Requested by: fluffy