Use rustls-platform-verifier for cert validation

This simplifies by removing the mutually exclusive `native-roots` and
`webpki-roots` features with something that is suitable for all
platforms.

crates/cli/src/commands/debug.rs

@@ -67,7 +67,7 @@ impl Options {
     #[tracing::instrument(skip_all)]
     pub async fn run(self, root: &super::Options) -> anyhow::Result<()> {
         use Subcommand as SC;
-        let http_client_factory = HttpClientFactory::new().await?;
+        let http_client_factory = HttpClientFactory::new();
         match self.subcommand {
             SC::Http {
                 show_headers,

crates/cli/src/commands/doctor.rs

@@ -41,7 +41,7 @@ impl Options {
         let config: RootConfig = root.load_config()?;
 
         // We'll need an HTTP client
-        let http_client_factory = HttpClientFactory::new().await?;
+        let http_client_factory = HttpClientFactory::new();
         let base_url = config.http.public_base.as_str();
         let issuer = config.http.issuer.as_ref().map(url::Url::as_str);
         let issuer = issuer.unwrap_or(base_url);

crates/cli/src/commands/server.rs

@@ -146,7 +146,7 @@ impl Options {
         )
         .await?;
 
-        let http_client_factory = HttpClientFactory::new().await?;
+        let http_client_factory = HttpClientFactory::new();
 
         let homeserver_connection = SynapseConnection::new(
             config.matrix.homeserver.clone(),

crates/cli/src/commands/worker.rs

@@ -55,7 +55,7 @@ impl Options {
         let mailer = mailer_from_config(&config.email, &templates)?;
         mailer.test_connection().await?;
 
-        let http_client_factory = HttpClientFactory::new().await?;
+        let http_client_factory = HttpClientFactory::new();
         let conn = SynapseConnection::new(
             config.matrix.homeserver.clone(),
             config.matrix.endpoint.clone(),