fix(manager/github-actions): don't pin partial ruby-versions

While looking at the fix for `actions/setup-java`, we noticed that the
`ruby/setup-ruby` may also be affected, as it notes:

> short version like '2.6', automatically using the latest release
> matching that version

As Ruby versioning treats `3.4` as a pinned version rather than a range,
we'd propose a patch upgrade rewriting it to `3.4.7`, losing the rolling
behaviour the workflow asked for.

We can reuse the `semver-partial` handling as a `partialValSchema`
helper, so short versions keep their precision and only exact versions
are looked up as pinned.

Co-authored-by: Claude Opus 5 <jamie.tanna+claude-code@mend.io>

lib/modules/manager/github-actions/extract.spec.ts

@@ -2525,6 +2525,8 @@ describe('modules/manager/github-actions/extract', () => {
       ],
     },
     {
+      // a short `ruby-version` is the latest release matching it, so it must
+      // keep its precision rather than gain a patch component
       step: {
         uses: 'ruby/setup-ruby@v1',
         with: { 'ruby-version': '3.4' },
@@ -2536,6 +2538,22 @@ describe('modules/manager/github-actions/extract', () => {
           depName: 'ruby',
           depType: 'uses-with',
           packageName: 'ruby',
+          versioning: 'semver-partial',
+        },
+      ],
+    },
+    {
+      step: {
+        uses: 'ruby/setup-ruby@v1',
+        with: { 'ruby-version': '3.4.7' },
+      },
+      expected: [
+        {
+          currentValue: '3.4.7',
+          datasource: 'ruby-version',
+          depName: 'ruby',
+          depType: 'uses-with',
+          packageName: 'ruby',
         },
       ],
     },

lib/modules/manager/github-actions/known-actions/ruby-version.ts

@@ -1,11 +1,14 @@
 import { RubyVersionDatasource } from '../../../datasource/ruby-version/index.ts';
 import type { KnownActionConfig } from '../types.ts';
-import { valSchema } from './utils.ts';
+import { partialValSchema } from './utils.ts';
 
 export const rubyVersionActions: Record<string, KnownActionConfig> = {
+  // https://github.com/ruby/setup-ruby
   'ruby/setup-ruby': {
     datasource: RubyVersionDatasource.id,
     packageName: 'ruby',
-    withSchema: valSchema('ruby-version'),
+    // a short `ruby-version` such as `3.3` means the latest release matching
+    // it, rather than a pinned version
+    withSchema: partialValSchema('ruby-version'),
   },
 };

lib/modules/manager/github-actions/known-actions/utils.ts

@@ -94,6 +94,18 @@ export function valSchema(
     .transform((val) => [parseValue(val[key], isInvalid)]);
 }
 
+/**
+ * As `valSchema`, for inputs which accept a partial version.
+ */
+export function partialValSchema(
+  key: string,
+  isInvalid?: (val: string) => boolean,
+): ActionSchema {
+  return z
+    .object({ [key]: z.string().optional() })
+    .transform((val) => [parsePartialValue(val[key], isInvalid)]);
+}
+
 export const VersionVal = valSchema('version');
 
 export function parseImageValue(image: string | undefined): PackageDependency {