openapi-generator-cli: fix stale patch url

[B4dM4n]

The upstream pull request URL is invalid now. Switch to the actual commit URL.

Followup of #483728

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

[SuperSandro2000]

The upstream pull request URL is invalid now. Switch to the actual commit URL.

? It is merged, nothing about the URL is invalid.

[B4dM4n]

Sorry, I mixed the description with another build failure I had.

The hash currently on master is outdated:

nix build github:NixOS/nixpkgs/987687fd632e#openapi-generator-cli
error: hash mismatch in fixed-output derivation '/nix/store/mg5r1jn0h1ab24wp6k7r8vjfwzc7ddrj-23326.patch.drv':
         specified: sha256-s68VoIXSFGvGCaFtCUYkeoq+CgC+2gIdDIIsmn8uqyk=
            got:    sha256-E1VgtaIW1V+8ch2RpW850fVNl5Iqitjog+0b8DKFgZw=
error: Cannot build '/nix/store/c51sywpyl884cs2y3q64j6nnq072ixwq-openapi-generator-cli-7.21.0.drv'.
       Reason: 1 dependency failed.
       Output paths:
         /nix/store/gyijxhi9gdrgqqjkfvqvqb82v8hkin60-openapi-generator-cli-7.21.0
error: Build failed due to failed dependency

And its referencing an unstable PR URL, which is also fixed by this change.

[mrdev023]

Same for me.