macros: Fix blueprint warnings

Author: bilelmoussaoui

CHANGELOG.md

@@ -93,7 +93,7 @@ yuraiz:
 ```rust
 #[derive(Debug, Default, gtk::CompositeTemplate)]
 #[template(string = "
-template MyWidget : Widget {
+template $MyWidget : Widget {
     Label label {
         label: 'foobar';
     }

gtk4-macros/src/lib.rs

@@ -156,7 +156,7 @@ pub fn include_blueprint(input: TokenStream) -> TokenStream {
 ///
 ///     #[derive(Debug, Default, gtk::CompositeTemplate)]
 ///     #[template(string = "
-///     template MyWidget : Widget {
+///     template $MyWidget : Widget {
 ///         Label label {
 ///             label: 'foobar';
 ///         }

gtk4-macros/tests/my_widget.blp

@@ -1,4 +1,4 @@
-template MyWidget5 {
+template $MyWidget5 {
     Label label {
         label: 'foobar';
     }

gtk4-macros/tests/templates.rs

@@ -206,7 +206,7 @@ mod imp4 {
 
     #[derive(Debug, Default, gtk::CompositeTemplate)]
     #[template(string = "
-    template MyWidget4 : Widget {
+    template $MyWidget4 : Widget {
         Label label {
             label: 'foobar';
         }