remove unnecessary where-clauses (#4023)

they may cause tachys to break with -Znext-solver

(cherry picked from commit f34e3a5)

Author: lcnr

tachys/src/reactive_graph/mod.rs

@@ -561,10 +561,7 @@ mod stable {
                 fn add_any_attr<NewAttr: Attribute>(
                     self,
                     _attr: NewAttr,
-                ) -> Self::Output<NewAttr>
-                where
-                    Self::Output<NewAttr>: RenderHtml,
-                {
+                ) -> Self::Output<NewAttr> {
                     todo!()
                 }
             }

tachys/src/view/template.rs

@@ -58,10 +58,7 @@ where
     fn add_any_attr<NewAttr: Attribute>(
         self,
         _attr: NewAttr,
-    ) -> Self::Output<NewAttr>
-    where
-        Self::Output<NewAttr>: RenderHtml,
-    {
+    ) -> Self::Output<NewAttr> {
         panic!("AddAnyAttr not supported on ViewTemplate");
     }
 }