Support `panic` and `let assert`

[lpil]

Hello!

The upcoming Gleam release as 2 syntax changes. panic (which can go anywhere an expression goes, like todo but without the string argument), and let assert <pattern> = <expression>, which is the new syntax for assert <pattern> = <expression>.

Thanks!

[inoas]

should assert simply be replaced by let assert or should both work?

[lpil]

Both are currently valid Gleam syntax.

[inoas]

https://github.com/gleam-lang/tree-sitter-gleam/pull/46 https://github.com/gleam-lang/tree-sitter-gleam/pull/48

[J3RN]

Closed by #46 and #50