Add TOML language formatting support to Prettier

Projects may use data files written in the TOML language. A common example of such is the `pyproject.toml` file present
in projects that use the Poetry Python package management tool (either for project code dependencies, or development
tools).

In cases where the TOML content is edited directly by human contributors, it will be useful to provide code formatting
infrastructure for TOML files, and to enforce consistent formatting. This is easily accomplished by adding TOML support
to the existing code formatting infrastructure via the "prettier-plugin-toml" plugin for the Prettier formatting tool.

Poetry's `poetry.lock` file is also written in the TOML language. This file is automatically generated and never
manually edited. In this case, the automatically generated content is accepted as-is. So Prettier is configured to
exclude the `poetry.lock` file from formatting.

Author: per1234

.github/workflows/check-prettier-formatting-task.yml

@@ -90,6 +90,13 @@ on:
       - "**.mkdn?"
       - "**.ronn"
       - "**.workbook"
+      # TOML
+      - "**/Cargo.lock"
+      - "**/Cargo.toml.orig"
+      - "**/Gopkg.lock"
+      - "**/Pipfile"
+      - "**/pdm.lock"
+      - "**.toml"
       # YAML
       - "**/.clang-format"
       - "**/.clang-tidy"
@@ -187,6 +194,13 @@ on:
       - "**.mkdn?"
       - "**.ronn"
       - "**.workbook"
+      # TOML
+      - "**/Cargo.lock"
+      - "**/Cargo.toml.orig"
+      - "**/Gopkg.lock"
+      - "**/Pipfile"
+      - "**/pdm.lock"
+      - "**.toml"
       # YAML
       - "**/.clang-format"
       - "**/.clang-tidy"

.prettierignore

@@ -8,6 +8,7 @@
 /.licenses/
 __pycache__/
 node_modules/
+poetry.lock
 
 # Test files
 /internal/rule/schema/testdata/input/invalid-schema.json

.prettierrc

@@ -1,4 +1,5 @@
 {
+  "plugins": ["prettier-plugin-toml"],
   "semi": false,
   "printWidth": 120,
   "overrides": [

package-lock.json

@@ -5,7 +5,8 @@
     "github-label-sync": "3.0.0",
     "markdown-link-check": "3.13.7",
     "markdownlint-cli": "0.45.0",
-    "prettier": "3.6.2"
+    "prettier": "3.6.2",
+    "prettier-plugin-toml": "2.0.6"
   },
   "engines": {
     "node": "20.x"