We dont control the test output and sometimes see badly encoded characters.
These don't affect the operation of the code we're running. Use
errors='replace' to avoid those issues and the resulting test failures.
(From OE-Core rev: 3939b1923387d3bc440118ed1663d28a03a1ea5d)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>