MAINT: Update rust version for dev/CI to 1.32

Newer rand versions require newer Rust, and we only need it for testing,
so it's no big deal.

Author: bluss

.travis.yml

@@ -6,7 +6,8 @@ matrix:
     - rust: 1.18.0
       env:
        - SKIP_TEST=1
-    - rust: 1.30.0
+    - rust: 1.32.0
+    - rust: 1.34.2
     - rust: stable
       env:
        - FEATURES='serde-1'

src/lib.rs

@@ -26,7 +26,7 @@
 //!
 //! ### Rust Version
 //!
-//! This version of indexmap requires Rust 1.18 or later, or 1.30+ for
+//! This version of indexmap requires Rust 1.18 or later, or 1.32+ for
 //! development builds, and Rust 1.36+ for using with `alloc` (without `std`),
 //! see below.
 //!