Add CI for de-facto minimum Rust version, 1.30.0

SimonSapin · SimonSapin · commit eef8622f3661 · 2019-04-24T15:42:50.000+02:00
That’s when `trim_start` was added
diff --git a/.travis.yml b/.travis.yml
@@ -3,6 +3,7 @@ rust:
   - nightly
   - beta
   - stable
+  - 1.30.0
 
 script:
   - cargo build --verbose

-Original file line number
+Diff line change
   - nightly
   - beta
   - stable
 +  - 1.30.0
 script:
   - cargo build --verbose