Bumping minimum version to Rust 1.49.0 due to:

stmpjmpr · stmpjmpr · commit 05f511648626 · 2022-02-24T22:03:48.000-08:00
- rust-lang/rust#55002 - rust-lang/rust#70921
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,6 @@
 language: rust
 rust:
-- 1.46.0
+- 1.49.0
 - stable
 - beta
 - nightly

-Original file line number
+Diff line change
 language: rust
 rust:
 -- 1.46.0
 +- 1.49.0
 - stable
 - beta
 - nightly