chore: drop minio/sha256-simd

[rootulp]

Closes #161
Blocked on #263

Testing

The BenchmarkEDSRoots benchmark behaves similarly before and after this PR. Since it is computing roots, I assume the SHA256 operations for minio/sha256-simd and Go 1.21's crypto/sha256 perform similarly.

Before

Running tool: /usr/local/go/bin/go test -benchmem -run=^$ -bench ^BenchmarkEDSRoots$ github.com/celestiaorg/rsmt2d

goos: darwin
goarch: arm64
pkg: github.com/celestiaorg/rsmt2d
BenchmarkEDSRoots/32x32x512_ODS-10         	    1063	   1169687 ns/op	 1791189 B/op	   34052 allocs/op
BenchmarkEDSRoots/64x64x512_ODS-10         	     392	   3056992 ns/op	 6203578 B/op	  133636 allocs/op
BenchmarkEDSRoots/128x128x512_ODS-10       	     100	  10686539 ns/op	26235561 B/op	  530437 allocs/op
BenchmarkEDSRoots/256x256x512_ODS-10       	      31	  42617637 ns/op	106996448 B/op	 2110469 allocs/op
BenchmarkEDSRoots/512x512x512_ODS-10       	       7	 158435357 ns/op	490824795 B/op	 8419427 allocs/op
PASS
ok  	github.com/celestiaorg/rsmt2d	9.528s

After

Running tool: /usr/local/go/bin/go test -benchmem -run=^$ -bench ^BenchmarkEDSRoots$ github.com/celestiaorg/rsmt2d

goos: darwin
goarch: arm64
pkg: github.com/celestiaorg/rsmt2d
BenchmarkEDSRoots/32x32x512_ODS-10         	    1010	   1168943 ns/op	 1793211 B/op	   34052 allocs/op
BenchmarkEDSRoots/64x64x512_ODS-10         	     381	   3175877 ns/op	 6207691 B/op	  133636 allocs/op
BenchmarkEDSRoots/128x128x512_ODS-10       	     100	  10775309 ns/op	26243828 B/op	  530438 allocs/op
BenchmarkEDSRoots/256x256x512_ODS-10       	      32	  69096212 ns/op	107013057 B/op	 2110472 allocs/op
BenchmarkEDSRoots/512x512x512_ODS-10       	       7	 158312988 ns/op	490854710 B/op	 8419386 allocs/op
PASS
ok  	github.com/celestiaorg/rsmt2d	9.516s

[codecov]

Codecov Report

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@@           Coverage Diff           @@
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  Files           ?        7           
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  Branches        ?        0           
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  Hits            ?      641           
  Misses          ?      110           
  Partials        ?       42           

Files Changed	Coverage Δ
tree.go	100.00% <ø> (ø)