[BUG] Incorrect DC blocker frequency response

[jatinchowdhury18]

Describe the bug
From user email:

When I added the plugin to a drum set with a really sub-heavy kick drum I noticed that it lost a lot of it's weight. It seems like there is a high pass filter at 70Hz at any settings with the plugin. I think it would be a great improvement if you removed this high pass filter. Here is a frequency analyzer graph of this:

Expected behavior
CHOW Tape should attenuate signals at DC, but not at audible low frequencies.

Desktop (please complete the following information):
Probably all versions.

[jatinchowdhury18]

#83 Fixes this bug by upgrading the DC blocker to a 4th-order Butterworth HPF. The new frequency response stays with 1dB of unity down to 40 Hz.