build(cargo)!: change MSRV 1.78.0 -> 1.81.0

BREAKING CHANGE: This bumps the minimum supported rust version (MSRV) to
1.81.0 since one of the crates used by `git2` requires this bump. We
have to follow latest `git2` updates as much as possible, since it
has high potential to fix security issues

Signed-off-by: Christina Sørensen <ces@fem.gg>

Cargo.toml

@@ -6,7 +6,7 @@ description = "A modern replacement for ls"
 authors = ["Christina Sørensen <christina@cafkafk.com>"]
 categories = ["command-line-utilities"]
 edition = "2021"
-rust-version = "1.78.0"
+rust-version = "1.81.0"
 exclude = [
   "/docs/",
   "/devtools/",

rust-toolchain.toml

@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: EUPL-1.2
 [toolchain]
 # NOTE: don't forget to update the unit-tests workflow when changing this
-channel = "1.78"
+channel = "1.81"
 components = [
   "rustfmt",
   "rustc",