Regression on devel - concat (and display) does not compile anymore
`nimble test` and any proc that relies on `concat` including tensor display fails to compile on Nim devel.

Error is:

```
../src/tensor/display.nim(25, 27) template/generic instantiation of `disp3d` from here
../src/tensor/private/p_display.nim(94, 20) template/generic instantiation of `concat` from here
../src/tensor/shapeshifting.nim(211, 43) Error: type mismatch: got <HSlice[system.int, system.int], int literal(1)>
but expected one of:
proc `|`(a, b: typedesc): typedesc
  first type mismatch at position: 1
  required type: typedesc
  but expression '
0 .. pred(it, 1)' is of type: HSlice[system.int, system.int]

expression:
  0 .. pred(it, 1) | 1
```

Related: https://github.com/nim-lang/Nim/commit/f6def4286c12a2c4a68a3d9e04d562359aeb160b, https://github.com/nim-lang/Nim/issues/8603 and https://github.com/nim-lang/Nim/issues/8677

It seems like `|` is resolved too early and the compiler doesn't see:

https://github.com/mratsim/Arraymancer/blob/0a08949030ceb0ca5499f73e4b6bca280bec774d/src/tensor/accessors_macros_syntax.nim#L110-L131