Update askama version to 0.15.2 (#16472)

Improves a few things, in particular for warnings.

changelog: none

Author: samueltardieu

Cargo.toml

@@ -42,7 +42,7 @@ walkdir = "2.3"
 filetime = "0.2.9"
 itertools = "0.12"
 pulldown-cmark = { version = "0.11", default-features = false, features = ["html"] }
-askama = { version = "0.15", default-features = false, features = ["alloc", "config", "derive"] }
+askama = { version = "0.15.2", default-features = false, features = ["alloc", "config", "derive"] }
 
 [dev-dependencies.toml]
 version = "0.9.7"