Fix cargo equip error when expanding procedural macros

[dewa251202]

The error that I got was the following

error: could not bundle the code

- `memoise 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)` as `crate::__cargo_equip::crates::memoise`


Caused by:
  proc-macro server's api version (3) is newer than rust-analyzer's (2)

To fix it, I updated the code in ra_proc_macro to use newer ra_ap_proc_macro_api version.