Silence `email_eid` unused warning

Silence this warning:

    warning: value assigned to `email_eid` is never read
      --> src/main.rs:44:9
       |
    44 |     let mut email_eid = String::new();
       |         ^^^^^^^^^^^^^
       |
       = note: `#[warn(unused_assignments)]` on by default
       = help: maybe it is overwritten before being read?

    warning: 1 warning emitted

We are reading the variable, but only if `should_read_email`.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/main.rs b/src/main.rs
index c71a44d..a01d6f7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -41,7 +41,10 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     let mut action_opt: Option<EventResponseStatus> = None;
     let mut should_read_email = false;
+
+    #[allow(unused_assignments)]
     let mut email_eid = String::new();
+
     let mut event_ids = Vec::new();
 
     for arg in &args[1..] {