Bump github.com/sagernet/sing from 0.2.0 to 0.2.1

Bumps [github.com/sagernet/sing](https://github.com/sagernet/sing) from 0.2.0 to 0.2.1.
- [Release notes](https://github.com/sagernet/sing/releases)
- [Commits](https://github.com/sagernet/sing/compare/v0.2.0...v0.2.1)

---
updated-dependencies:
- dependency-name: github.com/sagernet/sing
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

go.mod

@@ -13,7 +13,7 @@ require (
 	github.com/pires/go-proxyproto v0.7.0
 	github.com/quic-go/quic-go v0.33.0
 	github.com/refraction-networking/utls v1.3.1
-	github.com/sagernet/sing v0.2.0
+	github.com/sagernet/sing v0.2.1
 	github.com/sagernet/sing-shadowsocks v0.2.0
 	github.com/sagernet/wireguard-go v0.0.0-20221116151939-c99467f53f2c
 	github.com/seiflotfy/cuckoofilter v0.0.0-20220411075957-e3b120b3f5fb

go.sum

@@ -141,8 +141,8 @@ github.com/refraction-networking/utls v1.3.1/go.mod h1:kHXvVB66a4BzVRYC4Em7e1HAf
 github.com/riobard/go-bloom v0.0.0-20200614022211-cdc8013cb5b3 h1:f/FNXud6gA3MNr8meMVVGxhp+QBTqY91tM8HjEuMjGg=
 github.com/riobard/go-bloom v0.0.0-20200614022211-cdc8013cb5b3/go.mod h1:HgjTstvQsPGkxUsCd2KWxErBblirPizecHcpD3ffK+s=
 github.com/russross/blackfriday v1.5.2/go.mod h1:JO/DiYxRf+HjHt06OyowR9PTA263kcR/rfWxYHBV53g=
-github.com/sagernet/sing v0.2.0 h1:iyc4TaeXG5XYXixl48zSDDTw46C9NOEAVFq6ZE0dA2k=
-github.com/sagernet/sing v0.2.0/go.mod h1:9uHswk2hITw8leDbiLS/xn0t9nzBcbePxzm9PJhwdlw=
+github.com/sagernet/sing v0.2.1 h1:r0STYeyfKBBtoAHsBtW1dQonxG+3Qidde7/1VAMhdn8=
+github.com/sagernet/sing v0.2.1/go.mod h1:9uHswk2hITw8leDbiLS/xn0t9nzBcbePxzm9PJhwdlw=
 github.com/sagernet/sing-shadowsocks v0.2.0 h1:ILDWL7pwWfkPLEbviE/MyCgfjaBmJY/JVVY+5jhSb58=
 github.com/sagernet/sing-shadowsocks v0.2.0/go.mod h1:ysYzszRLpNzJSorvlWRMuzU6Vchsp7sd52q+JNY4axw=
 github.com/sagernet/wireguard-go v0.0.0-20221116151939-c99467f53f2c h1:vK2wyt9aWYHHvNLWniwijBu/n4pySypiKRhN32u/JGo=