fix: upgrade google-gmail1 to v7 to resolve security advisory

Upgrade google-gmail1 from 6.0.0 to 7.0.0 which uses yup-oauth2 v12
that no longer depends on the unmaintained rustls-pemfile crate.

This resolves RUSTSEC-2025-0134 (rustls-pemfile unmaintained).

Breaking changes addressed:
- Updated InstalledFlowAuthenticator to use CustomHyperClientBuilder
- Added hyper-rustls with http1 feature for OAuth redirect flow

Signed-off-by: Jeremiah Russell <jerry@jrussell.ie>

src/gmail_client.rs

@@ -105,7 +105,7 @@ use google_gmail1::{
         client::legacy::{Client, connect::HttpConnector},
         rt::TokioExecutor,
     },
-    yup_oauth2::{InstalledFlowAuthenticator, InstalledFlowReturnMethod},
+    yup_oauth2::{CustomHyperClientBuilder, InstalledFlowAuthenticator, InstalledFlowReturnMethod},
 };
 
 mod message_summary;
@@ -259,10 +259,11 @@ impl GmailClient {
         let client = Client::builder(executor.clone()).build(connector.clone());
         log::trace!("file to persist tokens to `{}`", config.persist_path());
 
+        let auth_client = Client::builder(executor).build(connector);
         let auth = InstalledFlowAuthenticator::with_client(
             config.secret().clone(),
             InstalledFlowReturnMethod::HTTPRedirect,
-            Client::builder(executor).build(connector),
+            CustomHyperClientBuilder::from(auth_client),
         )
         .persist_tokens_to_disk(config.persist_path())
         .build()