Are there any viruses or bacteria which have evolved to withstand higher temperatures due to fever
Fever is just one of the many ways of the body's defense mechanism work. Under infection, human body can raise body temperature, release cytokins and activate white blood cells etc. Sometimes the bacteria can evade immune suppression or immune complement fixation so that they can stay inside a "fever-ish" body like they just don't care. Example: Pseudomonas aeruginosa. They can grow in 42 degree Celsius which surpass the normal fever temperature.

My answer may not be the best for your question. All I'm trying to say is that fever acts as a supportive role during an infection. Human body relies on heavy artilleries such as white blood cells and cytokin to clear the infection. That's why it will be more beneficial for the bacteria to evolve abilities to evade immune suppression and immune complement fixation. And bacteria know how to do those.