feat: support is_collaborators (#304)

* feat: support is_collaborators

* add an example

examples/is_collab.rs

@@ -0,0 +1,18 @@
+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 octocrab = Octocrab::builder().personal_token(token).build()?;
+
+    let repo = octocrab.repos("rust-lang", "rust").is_collaborator("Roger-luo").await?;
+
+    if repo {
+        println!("Roger-luo is a collaborator of rust-lang/rust");
+    } else {
+        println!("Roger-luo is not a collaborator of rust-lang/rust");
+    }
+
+    Ok(())
+}

src/api/repos.rs

@@ -521,4 +521,19 @@ impl<'octo> RepoHandler<'octo> {
         ))?;
         self.crab._get(url, None::<&()>).await
     }
+
+    /// Check if a user is a repository collaborator
+    pub async fn is_collaborator(
+        &self,
+        username: impl AsRef<str>,
+    ) -> Result<bool> {
+        let url = self.crab.absolute_url(format!(
+            "/repos/{owner}/{repo}/collaborators/{username}",
+            owner = self.owner,
+            repo = self.repo,
+            username = username.as_ref(),
+        ))?;
+        let response = self.crab._get(url, None::<&()>).await?;
+        Ok(response.status().is_success())
+    }
 }