Update RPC URL environment variable

Replaced INFURA_API_KEY with MAINNET_RPC_URL for consistency and clarity. Updated the test setup to use the new MAINNET_RPC_URL for fetching the RPC URL from the environment variables.

.github/workflows/rust.yml

@@ -8,7 +8,7 @@ on:
 
 env:
   CARGO_TERM_COLOR: always
-  INFURA_API_KEY: ${{ secrets.INFURA_API_KEY }}
+  MAINNET_RPC_URL: ${{ secrets.MAINNET_RPC_URL }}
 
 jobs:
   lint:

src/tests.rs

@@ -9,12 +9,7 @@ use once_cell::sync::Lazy;
 pub(crate) static BLOCK_NUMBER: Lazy<BlockId> = Lazy::new(|| BlockId::from(17000000));
 pub(crate) static RPC_URL: Lazy<Url> = Lazy::new(|| {
     dotenv().ok();
-    format!(
-        "https://mainnet.infura.io/v3/{}",
-        std::env::var("INFURA_API_KEY").unwrap()
-    )
-    .parse()
-    .unwrap()
+    std::env::var("MAINNET_RPC_URL").unwrap().parse().unwrap()
 });
 pub(crate) static PROVIDER: Lazy<ReqwestProvider> =
     Lazy::new(|| ProviderBuilder::new().on_http(RPC_URL.clone()));