Reduce MSRV to 1.63

Author: djc

.github/workflows/rust.yml

@@ -32,7 +32,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
-          toolchain: "1.65.0"
+          toolchain: "1.63.0"
       - run: cargo check --lib --all-features
 
   lint:

Cargo.toml

@@ -2,7 +2,7 @@
 name = "gcp_auth"
 version = "0.9.0"
 edition = "2021"
-rust-version = "1.65"
+rust-version = "1.63"
 repository = "https://github.com/hrvolapeter/gcp_auth"
 description = "Google cloud platform (GCP) authentication using default and custom service accounts"
 documentation = "https://docs.rs/gcp_auth/"