build(deps): bump github.com/quic-go/quic-go from 0.39.4 to 0.42.0 (#25)

* build(deps): bump github.com/quic-go/quic-go from 0.39.4 to 0.42.0

Bumps [github.com/quic-go/quic-go](https://github.com/quic-go/quic-go) from 0.39.4 to 0.42.0.
- [Release notes](https://github.com/quic-go/quic-go/releases)
- [Changelog](https://github.com/quic-go/quic-go/blob/master/Changelog.md)
- [Commits](https://github.com/quic-go/quic-go/compare/v0.39.4...v0.42.0)

---
updated-dependencies:
- dependency-name: github.com/quic-go/quic-go
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

* bump: go minimum version 1.21

Signed-off-by: Gaukas Wang <i@gaukas.wang>

* update: github action scripts Go version

Signed-off-by: Gaukas Wang <i@gaukas.wang>

---------

Signed-off-by: dependabot[bot] <support@github.com>
Signed-off-by: Gaukas Wang <i@gaukas.wang>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Gaukas Wang <i@gaukas.wang>

go.mod

@@ -1,6 +1,6 @@
 module github.com/refraction-networking/uquic
 
-go 1.20
+go 1.21
 
 require (
 	github.com/francoispqt/gojay v1.2.13
@@ -9,7 +9,7 @@ require (
 	github.com/onsi/gomega v1.29.0
 	github.com/quic-go/qpack v0.4.0
 	github.com/refraction-networking/utls v1.5.4
-	go.uber.org/mock v0.3.0
+	go.uber.org/mock v0.4.0
 	golang.org/x/crypto v0.17.0
 	golang.org/x/exp v0.0.0-20231006140011-7918f672742d
 	golang.org/x/net v0.17.0
@@ -27,7 +27,7 @@ require (
 	github.com/google/gopacket v1.1.19 // indirect
 	github.com/google/pprof v0.0.0-20231023181126-ff6d637d2a7b // indirect
 	github.com/klauspost/compress v1.17.2 // indirect
-	github.com/quic-go/quic-go v0.39.4 // indirect
+	github.com/quic-go/quic-go v0.42.0 // indirect
 	golang.org/x/mod v0.13.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
 	golang.org/x/tools v0.14.0 // indirect