build(deps): bump lukechampine.com/frand

Bumps the all-dependencies group with 1 update in the / directory: [lukechampine.com/frand](https://github.com/lukechampine/frand).


Updates `lukechampine.com/frand` from 1.4.2 to 1.5.1
- [Commits](lukechampine/frand@v1.4.2...v1.5.1)

---
updated-dependencies:
- dependency-name: lukechampine.com/frand
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: all-dependencies
...

Signed-off-by: dependabot[bot] <[email protected]>

go.mod

@@ -1,13 +1,11 @@
 module go.sia.tech/mux
 
 go 1.23
+toolchain go1.23.4
 
 require (
 	golang.org/x/crypto v0.31.0
-	lukechampine.com/frand v1.4.2
+	lukechampine.com/frand v1.5.1
 )
 
-require (
-	github.com/aead/chacha20 v0.0.0-20180709150244-8b13a72661da // indirect
-	golang.org/x/sys v0.28.0 // indirect
-)
+require golang.org/x/sys v0.28.0 // indirect

go.sum

@@ -1,9 +1,6 @@
-github.com/aead/chacha20 v0.0.0-20180709150244-8b13a72661da h1:KjTM2ks9d14ZYCvmHS9iAKVt9AyzRSqNU1qabPih5BY=
-github.com/aead/chacha20 v0.0.0-20180709150244-8b13a72661da/go.mod h1:eHEWzANqSiWQsof+nXEI9bUVUyV6F53Fp89EuCh2EAA=
 golang.org/x/crypto v0.31.0 h1:ihbySMvVjLAeSH1IbfcRTkD/iNscyz8rGzjF/E5hV6U=
 golang.org/x/crypto v0.31.0/go.mod h1:kDsLvtWBEx7MV9tJOj9bnXsPbxwJQ6csT/x4KIN4Ssk=
-golang.org/x/sys v0.0.0-20190626221950-04f50cda93cb/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.28.0 h1:Fksou7UEQUWlKvIdsqzJmUmCX3cZuD2+P3XyyzwMhlA=
 golang.org/x/sys v0.28.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-lukechampine.com/frand v1.4.2 h1:RzFIpOvkMXuPMBb9maa4ND4wjBn71E1Jpf8BzJHMaVw=
-lukechampine.com/frand v1.4.2/go.mod h1:4S/TM2ZgrKejMcKMbeLjISpJMO+/eZ1zu3vYX9dtj3s=
+lukechampine.com/frand v1.5.1 h1:fg0eRtdmGFIxhP5zQJzM1lFDbD6CUfu/f+7WgAZd5/w=
+lukechampine.com/frand v1.5.1/go.mod h1:4VstaWc2plN4Mjr10chUD46RAVGWhpkZ5Nja8+Azp0Q=