Bump MSRV to 1.70.0

The intention is to take advantage of `std::io::IsTerminal` that landed
in 1.70.0, both in `bat` and its dependencies (`clap`, `grep-cli`).

This will fix #2570 as well - `grep-cli` 0.1.9 has a patch for that.

Signed-off-by: mataha <mataha@users.noreply.github.com>

Cargo.toml

@@ -10,7 +10,7 @@ version = "0.23.0"
 exclude = ["assets/syntaxes/*", "assets/themes/*"]
 build = "build.rs"
 edition = '2018'
-rust-version = "1.64"
+rust-version = "1.70"
 
 [features]
 default = ["application"]
@@ -25,7 +25,6 @@ application = [
 # Mainly for developers that want to iterate quickly
 # Be aware that the included features might change in the future
 minimal-application = [
-    "is-terminal",
     "clap",
     "dirs",
     "paging",
@@ -41,7 +40,6 @@ regex-onig = ["syntect/regex-onig"] # Use the "oniguruma" regex engine
 regex-fancy = ["syntect/regex-fancy"] # Use the rust-only "fancy-regex" engine
 
 [dependencies]
-is-terminal = { version = "0.4.4", optional = true }
 nu-ansi-term = "0.47.0"
 ansi_colours = "^1.2"
 bincode = "1.0"
@@ -62,7 +60,7 @@ path_abs = { version = "0.5", default-features = false }
 clircle = "0.4"
 bugreport = { version = "0.5.0", optional = true }
 dirs = { version = "5.0.0", optional = true }
-grep-cli = { version = "0.1.7", optional = true }
+grep-cli = { version = "0.1.9", optional = true }
 regex = { version = "1.8.3", optional = true }
 walkdir = { version = "2.3", optional = true }
 bytesize = { version = "1.2.0" }
@@ -78,7 +76,7 @@ default-features = false
 features = ["parsing"]
 
 [dependencies.clap]
-version = "4.3.0"
+version = "4.4.0"
 optional = true
 features = ["wrap_help", "cargo"]
 
@@ -98,7 +96,7 @@ tempfile = "3.5.0"
 nix = { version = "0.26.2", default-features = false, features = ["term"] }
 
 [build-dependencies.clap]
-version = "4.1.8"
+version = "4.4.0"
 optional = true
 features = ["wrap_help", "cargo"]