Add PATCH support in Gitea client and update issue handling

Extend Gitea client with a `patch` method for executing PATCH requests. Introduce `IssueWriteSetBody` struct for serializing issue update payloads. Update Gitea action to append related issues and send PATCH requests to update issue descriptions.

src/gitea/client.rs

@@ -1,8 +1,9 @@
 use crate::config::{Config, GiteaConfig};
 use crate::error::GeneralError;
 use reqwest::header::{HeaderMap, ACCEPT, AUTHORIZATION};
-use reqwest::{ClientBuilder, StatusCode};
+use reqwest::{Body, ClientBuilder, StatusCode};
 use serde::de::DeserializeOwned;
+use serde::Serialize;
 use url::Url;
 
 #[derive(Debug)]
@@ -79,6 +80,38 @@ impl Client {
             }),
         }
     }
+
+    pub async fn patch<T: DeserializeOwned, B: Serialize>(
+        &self,
+        url: Url,
+        body: &B,
+    ) -> Result<T, GeneralError> {
+        let mut headers = HeaderMap::new();
+        headers.append(AUTHORIZATION, format!("token {}", self.token).parse()?);
+        headers.append(ACCEPT, "application/json".parse()?);
+
+        let client = ClientBuilder::new()
+            .default_headers(headers)
+            .build()
+            .unwrap();
+
+        let response = client.patch(url.clone()).json(body).send().await?;
+
+        match response.status() {
+            StatusCode::OK | StatusCode::CREATED => {
+                let result: T = response.json().await?;
+
+                Ok(result)
+            }
+            _ => Err(GeneralError {
+                description: format!(
+                    "Could not call PATCH on {:?}, error code {}",
+                    url,
+                    response.status()
+                ),
+            }),
+        }
+    }
 }
 
 #[cfg(test)]