Inline dependency-versions syntax (#2122)

* Write docs for inline dependency-versions

* Change the `inline` keyword to `packages` for better readability

* Implement inline package constraints

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Add schema for TOML properties

* Change the parsing of the option to parse filenames as-is

* Add a unit test for table-parsing of the option

* Remove unneeded shlex.quote on the dependency-version test

* Tidy-ups, comments, docs fixes

* Add test for empty packages option value

* Fix empty packages scenario

And, remove some optionals to reduce the problem space

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

bin/generate_schema.py

@@ -104,7 +104,24 @@ properties:
   dependency-versions:
     default: pinned
     description: Specify how cibuildwheel controls the versions of the tools it uses
-    type: string
+    oneOf:
+      - enum: [pinned, latest]
+      - type: string
+        description: Path to a file containing dependency versions, or inline package specifications, starting with "packages:"
+        not:
+          enum: [pinned, latest]
+      - type: object
+        additionalProperties: false
+        properties:
+          file:
+            type: string
+      - type: object
+        additionalProperties: false
+        properties:
+          packages:
+            type: array
+            items:
+              type: string
   enable:
     description: Enable or disable certain builds.
     oneOf: