gists+examples: Extend GistsHandler by adding star(...)

The `star(...)` function takes a `gist_id` and 'stars' it. Has no
observable effect on the gist if it is already starred.

examples/star_a_gist.rs

@@ -0,0 +1,16 @@
+use octocrab::Octocrab;
+
+#[tokio::main]
+async fn main() -> octocrab::Result<()> {
+    let token = std::env::var("GITHUB_TOKEN").expect("GITHUB_TOKEN env variable is required");
+    let gist_id = if let Some(gist_id) = std::env::args().nth(1) {
+        gist_id
+    } else {
+        eprintln!("error: Need to pass gist id on argv");
+        std::process::exit(1);
+    };
+
+    let octocrab = Octocrab::builder().personal_token(token).build()?;
+    octocrab.gists().star(gist_id).await?;
+    Ok(())
+}

src/api/gists.rs

@@ -122,6 +122,30 @@ impl<'octo> GistsHandler<'octo> {
     pub fn list_commits(&self, gist_id: impl Into<String>) -> list_commits::ListCommitsBuilder {
         list_commits::ListCommitsBuilder::new(self, gist_id.into())
     }
+
+    /// Star the given gist. See [GitHub API Documentation][docs] more
+    /// information about response data.
+    ///
+    /// ```no_run
+    /// # async fn run() -> octocrab::Result<()> {
+    /// let gist = octocrab::instance()
+    ///     .gists()
+    ///     .star("00000000000000000000000000000000")
+    ///     .await?;
+    /// # Ok(())
+    /// # }
+    ///
+    /// [docs]: https://docs.github.com/en/rest/gists/gists?apiVersion=2022-11-28#star-a-gist
+    /// ```
+    pub async fn star(&self, gist_id: impl AsRef<str>) -> Result<()> {
+        let gist_id = gist_id.as_ref();
+        // PUT returns the HTTP body of the response, map it to `()` on success
+        // Callers of the library don't care about the HTTP response body
+        self.crab
+            ._put(format!("/gists/{gist_id}/star"), None::<&()>)
+            .await
+            .map(|_| ())
+    }
 }
 
 #[derive(Debug)]