Remove mentions of salvo

I previously removed the `salvo` support from `askama_web` in [7bc35a9],
because -- IMHO -- “the project is in too bad a state”. My assessment
about the project did not improve, to be honest.

Related advisory: [GHSA-54m3-5fxr-2f3j].

[GHSA-54m3-5fxr-2f3j]: <https://redirect.github.com/salvo-rs/salvo/security/advisories/GHSA-54m3-5fxr-2f3j>
[7bc35a9]: <https://redirect.github.com/askama-rs/askama_web/commit/7bc35a932141dc1fa4f5207638fa9ae83d09e31f>

Author: Kijewski

.github/workflows/rust.yml

@@ -30,7 +30,7 @@ jobs:
       - run: |
           set -eu
           for PKG in \
-            bench-build examples/actix-web-app examples/axum-app examples/poem-app examples/rocket-app examples/salvo-app examples/warp-app fuzzing \
+            bench-build examples/actix-web-app examples/axum-app examples/poem-app examples/rocket-app examples/warp-app fuzzing \
             askama askama_derive askama_escape askama_macros askama_parser \
             testing testing-alloc testing-no-std testing-renamed
           do
@@ -129,7 +129,7 @@ jobs:
           cargo sort --check --check-format --grouped
           set -eu
           for PKG in \
-            bench-build examples/actix-web-app examples/axum-app examples/poem-app examples/rocket-app examples/salvo-app examples/warp-app fuzzing \
+            bench-build examples/actix-web-app examples/axum-app examples/poem-app examples/rocket-app examples/warp-app fuzzing \
             askama askama_derive askama_escape askama_macros askama_parser \
             testing testing-alloc testing-no-std testing-renamed
           do
@@ -171,7 +171,7 @@ jobs:
     strategy:
       matrix:
         package: [
-          bench-build, examples/actix-web-app, examples/axum-app, examples/poem-app, examples/rocket-app, examples/salvo-app, examples/warp-app, fuzzing,
+          bench-build, examples/actix-web-app, examples/axum-app, examples/poem-app, examples/rocket-app, examples/warp-app, fuzzing,
           askama, askama_derive, askama_escape, askama_macros, askama_parser,
           testing, testing-alloc, testing-no-std, testing-renamed,
         ]

book/src/frameworks.md

@@ -289,66 +289,6 @@ impl<'r> Responder<'r, 'static> for AppError {
 }
 ```
 
-## Salvo
-
-[![our salvo example web-app](
-    https://img.shields.io/badge/salvo-example-informational?style=flat-square&logo=git&logoColor=white&color=%23228b22
-)](
-    https://github.com/askama-rs/askama/tree/master/examples/salvo-app "our salvo example web-app"
-)
-[![crates.io: salvo](
-    https://img.shields.io/crates/v/salvo?label=salvo&style=flat-square&logo=rust&logoColor=white&color=informational
-)](
-    https://crates.io/crates/salvo "crates.io: salvo"
-)
-
-To convert the `String` to an HTML response, you can use
-[`Text::Html(_)`](https://docs.rs/salvo/0.76.0/salvo/prelude/enum.Text.html#variant.Html).
-
-```rust
-use salvo::writing::Text;
-use salvo::{Scribe, handler};
-
-#[handler]
-async fn handler() -> Result<impl Scribe, AppError> {
-    …
-    Ok(Text::Html(template.render()?))
-}
-```
-
-To implement your own error type, you can use this boilerplate code:
-
-```rust
-use askama::Template;
-use salvo::http::StatusCode;
-use salvo::writing::Text;
-use salvo::{Response, Scribe};
-
-#[derive(Debug, displaydoc::Display, thiserror::Error)]
-enum AppError {
-    /// could not render template
-    Render(#[from] askama::Error),
-}
-
-impl Scribe for AppError {
-    fn render(self, res: &mut Response) {
-        #[derive(Debug, Template)]
-        #[template(path = "error.html")]
-        struct Tmpl { … }
-
-        res.status_code(match &self {
-            AppError::Render(_) => StatusCode::INTERNAL_SERVER_ERROR,
-        });
-        let tmpl = Tmpl { … };
-        if let Ok(body) = tmpl.render() {
-            Text::Html(body).render(res);
-        } else {
-            Text::Plain("Something went wrong").render(res);
-        }
-    }
-}
-```
-
 ## Warp
 
 [![our warp example web-app](