ci/nixpkgs-vet: remove left-over pin

We're now consuming nixpkgs-vet from the pinned-nixpkgs, but apparently
forgot to remove all of this.

ci/README.md

@@ -20,23 +20,3 @@ Arguments:
 
 - `BASE_BRANCH`: The base branch to use, e.g. master or release-24.05
 - `REPOSITORY`: The repository from which to fetch the base branch. Defaults to <https://github.com/NixOS/nixpkgs.git>.
-
-## `ci/nixpkgs-vet`
-
-This directory contains scripts and files used and related to [`nixpkgs-vet`](https://github.com/NixOS/nixpkgs-vet/), which the CI uses to implement `pkgs/by-name` checks, along with many other Nixpkgs architecture rules.
-See also the [CI GitHub Action](../.github/workflows/nixpkgs-vet.yml).
-
-## `ci/nixpkgs-vet/update-pinned-tool.sh`
-
-Updates the pinned [`nixpkgs-vet` tool](https://github.com/NixOS/nixpkgs-vet) in [`ci/nixpkgs-vet/pinned-version.txt`](./nixpkgs-vet/pinned-version.txt) to the latest [release](https://github.com/NixOS/nixpkgs-vet/releases).
-
-Each release contains a pre-built `x86_64-linux` version of the tool which is used by CI.
-
-This script currently needs to be called manually when the CI tooling needs to be updated.
-
-Why not just build the tooling right from the PRs Nixpkgs version?
-
-- Because it allows CI to check all PRs, even if they would break the CI tooling.
-- Because it makes the CI check very fast, since no Nix builds need to be done, even for mass rebuilds.
-- Because it improves security, since we don't have to build potentially untrusted code from PRs.
-  The tool only needs a very minimal Nix evaluation at runtime, which can work with [readonly-mode](https://nixos.org/manual/nix/stable/command-ref/opt-common.html#opt-readonly-mode) and [restrict-eval](https://nixos.org/manual/nix/stable/command-ref/conf-file.html#conf-restrict-eval).

ci/nixpkgs-vet.sh

@@ -61,9 +61,6 @@ trace "Done"
 trace -n "Merging base branch into the HEAD commit in $tmp/merged.. "
 git -C "$tmp/merged" merge -q --no-edit "$baseSha"
 trace -e "\e[34m$(git -C "$tmp/merged" rev-parse HEAD)\e[0m"
-trace -n "Reading pinned nixpkgs-vet version from pinned-version.txt.. "
-toolVersion=$(<"$tmp/merged/ci/nixpkgs-vet/pinned-version.txt")
-trace -e "\e[34m$toolVersion\e[0m"
 
 trace "Running nixpkgs-vet.."
 nix-build ci -A nixpkgs-vet --argstr base "$tmp/base" --argstr head "$tmp/merged"

ci/nixpkgs-vet/pinned-version.txt

@@ -1 +0,0 @@
-0.1.4

ci/nixpkgs-vet/update-pinned-tool.sh

@@ -1,22 +0,0 @@
-#!/usr/bin/env nix-shell
-#!nix-shell -i bash -p jq curl
-
-set -o pipefail -o errexit -o nounset
-
-trace() { echo >&2 "$@"; }
-
-SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
-
-repository=NixOS/nixpkgs-vet
-pin_file=$SCRIPT_DIR/pinned-version.txt
-
-trace -n "Fetching latest release of $repository.. "
-latestRelease=$(curl -sSfL \
-  -H "Accept: application/vnd.github+json" \
-  -H "X-GitHub-Api-Version: 2022-11-28" \
-  https://api.github.com/repos/"$repository"/releases/latest)
-latestVersion=$(jq .tag_name -r <<< "$latestRelease")
-trace "$latestVersion"
-
-trace "Updating $pin_file"
-echo "$latestVersion" > "$pin_file"