feat(manager/asdf): support `asdf-plugin-manager` (#25539)

lib/modules/manager/asdf/extract.spec.ts

@@ -46,6 +46,7 @@ describe('modules/manager/asdf/extract', () => {
         codeBlock`
 adr-tools 3.0.0
 argocd 2.5.4
+asdf-plugin-manager 1.1.1
 awscli 2.8.6
 bun 0.2.2
 cargo-make 0.36.2
@@ -128,6 +129,13 @@ dummy 1.2.3
             depName: 'argocd',
             extractVersion: '^v(?<version>\\S+)',
           },
+          {
+            currentValue: '1.1.1',
+            datasource: 'github-releases',
+            packageName: 'asdf-community/asdf-plugin-manager',
+            depName: 'asdf-plugin-manager',
+            extractVersion: '^v(?<version>\\S+)',
+          },
           {
             currentValue: '2.8.6',
             datasource: 'github-tags',

lib/modules/manager/asdf/upgradeable-tooling.ts

@@ -54,6 +54,14 @@ export const upgradeableTooling: Record<string, ToolingDefinition> = {
       extractVersion: '^v(?<version>\\S+)',
     },
   },
+  'asdf-plugin-manager': {
+    asdfPluginUrl: 'https://github.com/asdf-community/asdf-plugin-manager',
+    config: {
+      datasource: GithubReleasesDatasource.id,
+      packageName: 'asdf-community/asdf-plugin-manager',
+      extractVersion: '^v(?<version>\\S+)',
+    },
+  },
   awscli: {
     asdfPluginUrl: 'https://github.com/MetricMike/asdf-awscli',
     config: {