fix: align prettier v2 -> v3 config to match pre-release workflow

Root cause of recurring lint failures on release PRs: the pre-release
workflow installed latest prettier (v3.x) to format docs/history.md,
but the pre-commit hook pinned mirrors-prettier at v2.5.1.

- Bump mirrors-prettier from v2.5.1 to v3.1.0 in .pre-commit-config.yaml
- Pin workflow to `prettier@3` to prevent future drift
- Add vendored assets (docs/diagram/, minified files) and Jinja
  templates to .prettierignore

One-time reformatting of existing files deferred to a separate PR.

Author: jstvz

.github/workflows/pre-release.yml

@@ -54,7 +54,7 @@ jobs:
                   python utility/update-history.py
             - name: Lint history
               run: |
-                  npm install prettier
+                  npm install prettier@3
                   npx prettier --write docs/history.md
             - name: Commit changes
               run: |

.pre-commit-config.yaml

@@ -23,7 +23,7 @@ repos:
           - id: isort
             args: ["--profile", "black", "--filter-files"]
     - repo: https://github.com/pre-commit/mirrors-prettier
-      rev: v2.5.1
+      rev: v3.1.0
       hooks:
           - id: prettier
     - repo: local

.prettierignore

@@ -1 +1,5 @@
-Test*.yaml
+Test*.yaml
+docs/diagram/
+**/*.min.js
+**/*.min.css
+cumulusci/files/templates/