Rework strawbs.png to make it suitable for dark theme

[adem4ik]

Fixes https://github.com/strawberrymusicplayer/strawberry/issues/926

Things done:

• Corrected color balance from mostly red to partially red / partially grey
• Upscaled using waifu2x including noise reduction and then downscaled back to original size to recover picture
• Optimized filesize via TinyPNG & FileOptimizer

[jonaski]

I'll test this out but I'm not sure it's visible enough to be usable with a dark theme.

[adem4ik]

I have another version. It was dropped cause it looks too dark in light theme. But works better in dark theme: strawbs_v2.zip

Here is comparison (v1, left - from my PR, v2 is from this message):

Let me know, if I should remake the PR.