[1.5.x] Modified a staticfiles test to use a unicode character that has just...

[1.5.x] Modified a staticfiles test to use a unicode character that has just one single representation. The previously used character (ş) has two different representations (u'\u015f' and u's\u0327'), which caused spurious failures when the tests were run across multiple platforms (e.g. on a Linux VM hosted on a Mac).