Replace GZIP compression with Brotli

[daxpedda]

Follow-up on #15. This replaces the GZIP compression with Brotli. This shouldn't be a problem as all browsers support Brotli nowadays, see https://caniuse.com/brotli.

My WASM files are now consistently about a third smaller.

[daxpedda]

This is a bit unfortunate, see hyperium/headers#116.

[jakobhellermann]

I noticed that with a large wasm file compression was taking a lot of time (~50s) so I looked at the brotli docs and it seems like the default compression level is 11.
I compiled a list of algorithm/level/size/speed combinations:

brotli [ 0] 21.76mb -> 8.53mb in 0.50
brotli [ 1] 21.76mb -> 8.17mb in 0.51
brotli [ 2] 21.76mb -> 5.23mb in 0.42
brotli [ 3] 21.76mb -> 4.88mb in 0.44
brotli [ 4] 21.76mb -> 4.53mb in 0.64
brotli [ 5] 21.76mb -> 4.60mb in 0.84
brotli [ 6] 21.76mb -> 4.53mb in 1.10
brotli [ 7] 21.76mb -> 4.36mb in 1.16
brotli [ 8] 21.76mb -> 4.35mb in 1.68
brotli [ 9] 21.76mb -> 3.56mb in 2.35
brotli [10] 21.76mb -> 3.20mb in 24.88
brotli [11] 21.76mb -> 3.08mb in 51.56
gzip  [ 0] 21.76mb -> 21.76mb in 0.32
gzip  [ 1] 21.76mb -> 6.87mb in 0.17
gzip  [ 2] 21.76mb -> 5.88mb in 0.25
gzip  [ 3] 21.76mb -> 5.51mb in 0.37
gzip  [ 4] 21.76mb -> 5.40mb in 0.40
gzip  [ 5] 21.76mb -> 5.34mb in 0.49
gzip  [ 6] 21.76mb -> 5.27mb in 0.83
gzip  [ 7] 21.76mb -> 5.25mb in 1.07
gzip  [ 8] 21.76mb -> 5.24mb in 1.29
gzip  [ 9] 21.76mb -> 5.24mb in 1.36

Looks like brotli definitely is the better option, but a compression level of 5 may be the best trade off.

[daxpedda]

50 sec is incredibly long ... LGTM.