Use new MaxMind env vars on Labrinth (#4573)

* Bring in modrinth-maxmind

* integrate modrinth-maxmind into labrinth

* Fix CI

packages/modrinth-util/src/lib.rs

@@ -0,0 +1,23 @@
+#![doc = include_str!("../README.md")]
+
+mod error;
+pub use error::*;
+
+use eyre::{Result, eyre};
+
+/// Fetches an environment variable, possibly loading it using [`dotenvy`].
+///
+/// # Errors
+///
+/// Errors if the environment variable is missing or empty, providing a
+/// pretty-printed error including the environment variable name.
+#[track_caller]
+pub fn env_var(key: &str) -> Result<String> {
+    let value = dotenvy::var(key)
+        .wrap_err_with(|| eyre!("missing environment variable `{key}`"))?;
+    if value.is_empty() {
+        Err(eyre!("environment variable `{key}` is empty"))
+    } else {
+        Ok(value)
+    }
+}