CompatHelper: bump compat for GPUCompiler to 0.23-0.26

[github-actions]

This pull request changes the compat entry for the GPUCompiler package from 0.21.4 to 0.21.4, 0.26.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

---

From #27 (comment):

Memo to self: replace

IPUToolkit.jl/src/compiler/compiler.jl

Lines 39 to 47 in 04b3c1f

	code = quote
	$GPUCompiler.@override($method_table, $ex)
	end
	if isdefined(Base.Experimental, Symbol("@overlay"))
	return esc(code)
	else
	push!(overrides, code)
	return
	end

with

    return esc(:( Base.Experimental.@overlay($method_table, $ex) ))

and require julia v1.8.

[giordano]

I verified locally that tests pass with hardware IPU with all minor versions of GPUCompiler 0.23-0.26, so this is ready to be merged.