chore: document minimal rust version in Cargo.toml

Sponsored-by: author

1 files changed, 1 insertions, 0 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 676f306..17535db 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,6 +7,7 @@ description = "a backup program"
 license = "AGPL-3.0-or-later"
 homepage = "https://obnam.org/"
 repository = "https://gitlab.com/larswirzenius/obnam"
+rust-version = "1.56.0"
 
 
 [dependencies]