cargo: set rust-version

This should hopefully make compilation errors from using
an older-than-supported compiler more helpful.

PR #2373 

1 files changed, 1 insertions, 0 deletions

diff --git a/Cargo.toml b/Cargo.toml
index fb78fcb4..84f00e7c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,6 +17,7 @@ exclude = ["HomebrewFormula"]
 build = "build.rs"
 autotests = false
 edition = "2018"
+rust-version = "1.65"
 
 [[bin]]
 bench = false