Come back to 1.31

Author: sylvestre

.github/workflows/CICD.yml

@@ -12,7 +12,7 @@ env:
   PROJECT_NAME: uutils
   PROJECT_DESC: "'Universal' (cross-platform) CLI utilities"
   PROJECT_AUTH: "uutils"
-  RUST_MIN_SRV: "1.32.0"
+  RUST_MIN_SRV: "1.31.0" ## v1.31.0 == "Rust 2018" (2018-12-06)
   RUST_COV_SRV: "2020-04-29" ## (~v1.45.0) supported rust version for code coverage; (date required/used by 'coverage') ## !maint: refactor when code coverage support is included in the stable channel
 
 on: [push, pull_request]