cli-plugins: remove deprecated Metadata.Experimental

This field was marked deprecated in 977d3ae,
which is part of Docker 20.10 and up.

This patch removes the field.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli-plugins/manager/metadata.go

@@ -22,8 +22,4 @@ type Metadata struct {
 	ShortDescription string `json:",omitempty"`
 	// URL is a pointer to the plugin's homepage.
 	URL string `json:",omitempty"`
-	// Experimental specifies whether the plugin is experimental.
-	//
-	// Deprecated: experimental features are now always enabled in the CLI
-	Experimental bool `json:",omitempty"`
 }