I think I have worked around the lifetime issue by keeping references to the intermediate str's.

src/render/renderer_integration.rs

@@ -2,11 +2,8 @@ use serde::Serialize;
 
 use crate::error::CustomError;
 
-pub(crate) trait RendererIntegration {
-    fn load_template<N, C>(&mut self, name: N, contents: C) -> Result<(), CustomError>
-    where
-        N: Into<String>,
-        C: AsRef<str>;
+pub(crate) trait RendererIntegration<'a> {
+    fn load_template(&mut self, name: &'a str, contents: &'a str) -> Result<(), CustomError>;
 
     fn render<C>(&self, context: C) -> Result<String, CustomError>
     where