Don't read version number from git repository.

See https://github.com/helix-editor/helix/issues/1603#issuecomment-1028104707

--- a/helix-term/build.rs
+++ b/helix-term/build.rs
@@ -1,22 +1,8 @@
 use helix_loader::grammar::{build_grammars, fetch_grammars};
-use std::borrow::Cow;
-use std::process::Command;
 
 const VERSION: &str = include_str!("../VERSION");
 
 fn main() {
-    let git_hash = Command::new("git")
-        .args(&["rev-parse", "HEAD"])
-        .output()
-        .ok()
-        .filter(|output| output.status.success())
-        .and_then(|x| String::from_utf8(x.stdout).ok());
-
-    let version: Cow<_> = match git_hash {
-        Some(git_hash) => format!("{} ({})", VERSION, &git_hash[..8]).into(),
-        None => VERSION.into(),
-    };
-
     if std::env::var("HELIX_DISABLE_AUTO_GRAMMAR_BUILD").is_err() {
         fetch_grammars().expect("Failed to fetch tree-sitter grammars");
         build_grammars().expect("Failed to compile tree-sitter grammars");
@@ -25,5 +11,5 @@
     println!("cargo:rerun-if-changed=../runtime/grammars/");
     println!("cargo:rerun-if-changed=../VERSION");
 
-    println!("cargo:rustc-env=VERSION_AND_GIT_HASH={}", version);
+    println!("cargo:rustc-env=VERSION_AND_GIT_HASH={}", VERSION);
 }