Log Message:
py-bitarray: updated to 1.9.0

2021-04-03   1.9.0:
-------------------
  * add shift operations (`<<`, `>>`, `<<=`, `>>=`)
  * add `bitarray.util.ba2base()` and `bitarray.util.base2ba()`,
    see last paragraph in [Bitarray representations](examples/represent.rst)
  * documentation and tests

2021-03-31   1.8.2:
-------------------
  * fix crash caused by unsupported types in binary operations
  * speedup initializing or extending a bitarray from another with different
    bit endianness
  * add formatting options to `bitarray.util.pprint()`
  * add documentation on [bitarray representations](examples/represent.rst)
  * add and improve tests (all 291 tests run in less than half a second on
    a modern machine)

2021-03-25   1.8.1:
-------------------
  * moved implementation of and `hex2ba()` and `ba2hex()` to C-level