only allow the HTTP/3 client to dial with a single QUIC version

[marten-seemann]

This is an unfortunate outcome, but we don't have any way to set the ALPN value based on the QUIC version in the client. It's better to throw an error than to offer an invalid combination of ALPN and QUIC version.

Depends on #2847.

[codecov]

Codecov Report

Merging #2848 into master will decrease coverage by 0.13%.
The diff coverage is 52.78%.

@@            Coverage Diff             @@
##           master    #2848      +/-   ##
==========================================
- Coverage   85.80%   85.67%   -0.13%     
==========================================
  Files         134      134              
  Lines        9065     9087      +22     
==========================================
+ Hits         7778     7785       +7     
- Misses        946      960      +14     
- Partials      341      342       +1     

Impacted Files	Coverage Δ
internal/qtls/go114.go	25.93% <0.00%> (-24.07%)	⬇️
internal/qtls/go115.go	46.67% <0.00%> (-3.33%)	⬇️
http3/roundtrip.go	93.22% <50.00%> (-3.21%)	⬇️
http3/server.go	65.00% <66.67%> (+0.14%)	⬆️
http3/client.go	86.92% <100.00%> (+0.74%)	⬆️
internal/protocol/version.go	100.00% <100.00%> (ø)

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