Cyclic reference involving class Context

[b-studios]

This PR is a minimalization of an incremental compilation error that we consistently hit, when modifying our Typer.scala.

(reported here: https://github.com/scala/scala3/issues/20245)

Steps to reproduce:

sbt> clean
sbt> compile

Modify a line in Typer.scala

https://github.com/effekt-lang/effekt/blob/34b9e79126db91604df4785aaabace15d154f8cb/effekt/shared/src/main/scala/effekt/Typer.scala#L12-L21

sbt> compile

Observed result:

[error] -- [E046] Cyclic Error: /private/tmp/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:15:57
[error] 15 |  private[typer] val unification = new Unification(using this)
[error]    |                                                         ^
[error]    |                                Cyclic reference involving class Context
[error]    |
[error]    | longer explanation available when compiling with `-explain`
[error] one error found
[error] (root / Compile / compileIncremental) Compilation failed