add archival notice to README

This repository is being archived. Point readers at the standard-library
or community package that replaces it.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -1,26 +0,0 @@
-# Vet and test the package. This is a pure Go library -- no build
-# step, no services -- so CI just runs `go vet` then `go test` on
-# every push to main and every pull request.
-
-name: CI
-
-on:
-  push:
-    branches:
-      - main
-  pull_request:
-  workflow_dispatch:
-
-jobs:
-  test:
-    runs-on: ubuntu-latest
-    container:
-      image: golang:1.21-alpine
-    steps:
-      - name: Install checkout dependencies
-        run: apk add --no-cache git nodejs
-      - uses: actions/checkout@v4
-      - name: go vet
-        run: go vet ./...
-      - name: go test
-        run: go test ./...

.github/workflows/test.yml

@@ -0,0 +1,47 @@
+name: Test
+
+on:
+  pull_request:
+    branches:
+      - develop
+  push:
+    branches:
+      - develop
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: ^1.21.0
+
+      - name: Display Go version
+        run: go version
+
+      - name: Install dependencies
+        run: go get
+
+      - name: Run tests
+        run: go test -v
+
+  notify:
+    name: Send Discord workflow notification
+    runs-on: ubuntu-latest
+    needs: test
+    steps:
+      - name: Send notification
+        uses: annybs/action-notify-discord@v1
+        if: ${{ always() }}
+        with:
+          repository: ${{ github.repository }}
+          result: ${{ needs.test.result }}
+          run-id: ${{ github.run_id }}
+          run-number: ${{ github.run_number }}
+          webhook-url: ${{ secrets.DISCORD_WEBHOOK }}
+          workflow: ${{ github.workflow }}

README.md

@@ -1,3 +1,17 @@
+> [!IMPORTANT]
+> **This repository is archived and no longer maintained.**
+>
+> The version parser here does not implement Semantic Versioning precedence
+> correctly (pre-release identifiers are ignored when ordering), and this
+> problem is solved well by maintained libraries.
+>
+> **Use instead:**
+> - [`github.com/Masterminds/semver/v3`](https://github.com/Masterminds/semver) — parsing, comparison, and constraint matching (replaces `Version` and `Constraint`).
+> - [`golang.org/x/mod/semver`](https://pkg.go.dev/golang.org/x/mod/semver) — if you only need to compare canonical `vX.Y.Z` strings.
+> - The `Migration` up/down helper had no third-party equivalent and was only used by `go/sqaffold` (also archived). For database migrations use [`github.com/pressly/goose`](https://github.com/pressly/goose).
+
+---
+
 # Go Version
 
 A simple library for parsing and comparing versions according to [Semantic Versioning 2.0.0](https://semver.org/).