onnx==1.5.0 breaks the TopK op in dev

this changed in the latest Brevitas export

Add test for export of QuantReLu and add new test cases for QuantHardTanh export 

Merge branch 'feature/quant_activation_tests' of github.com:quetric/finn into feature/quant_activation_tests

Scaled and non-scaled QuantHardTanh activation tests separated. Non-scaled test includes cases with scale parameter == 1. In scaled test, bipolar activation is excluded as it's not currently supported

Feature/adjusting clk frequency

[Test] Change input argument to clock period for make_pynq_proj and create_stitched_ip  transformation

[Transformation] Add warning if chosen clock period could lead to failure due to clock divider constraints