chore: upgrade to Go 1.21 (backport #2333)

[mergify]

Backport #2333 to v1.x

[cmwaters]

Looks like this is breaking some test:

invalid Bech32 prefix; expected celestia, got cosmos

Did we observe this when bumping to 1.21 on main?

[evan-forbes]

not afaik, that's really weird

[rootulp]

Nope, did not observe on main. Will look into it

[rootulp]

The error here

0.175 invalid value "1.21" for flag -compat: maximum supported Go version is 1.20

should be resolved by #2345

[rootulp]

Created #2363 b/c the issue reproduces on the v1.x branch

[rootulp]

That was misleading, this issue doesn't repro on v1.x with Go 1.20 so closed #2363

[rootulp]

Notes:

• Tests are consistently failing on this PR but not on main. See https://github.com/celestiaorg/celestia-app/actions/runs/5955618298/job/16155350427
• main's payforblob_factory.go doesn't contain MultiBlobTx b/c it was removed in chore: remove old signer and refactor tests #2314
• v1.x's payforblob_factory.go contains MultiBlobTx which is throwing an error b/c it expects celestia prefix but cosmos is used... cosmos1g39egf59z8tud3lcyjg5a83m20df4kcchmmsvv
• The v1.x to main diff

[evan-forbes]

do we just need to import the app into whatever tests as to run this then?

celestia-app/app/config.go

Lines 7 to 13 in a0a6e4b

	func init() {
	cfg := sdk.GetConfig()
	cfg.SetBech32PrefixForAccount(Bech32PrefixAccAddr, Bech32PrefixAccPub)
	cfg.SetBech32PrefixForValidator(Bech32PrefixValAddr, Bech32PrefixValPub)
	cfg.SetBech32PrefixForConsensusNode(Bech32PrefixConsAddr, Bech32PrefixConsPub)
	cfg.Seal()
	}

[rootulp]

I'm not sure what you mean, do you mind rephrasing? I'm currently stuck here: #2375 (comment)

[rootulp]

It looks like Go 1.21 is breaking for us b/c the the behavior of init() command changed (as @evan-forbes referenced above)

Source: https://tip.golang.org/doc/go1.21