Set default-features = false on git2 to reduce dependencies and binary size

With current git2, this reduces lstr from 144 dependencies to 137, and
from 4.3M to 3.6M.

With rust-lang/git2-rs#1168 merged into upstream
git2-rs, it further reduces lstr to 107 dependencies (though with
negligible additional improvement to binary size as the additional
dependencies were compiled out).

Author: joshtriplett

Cargo.lock

@@ -16,7 +16,7 @@ anyhow = "1.0"
 colored = "2.1.0"
 clap = { version = "4.5.7", features = ["derive"] }
 crossterm = "0.27.0"
-git2 = "0.19.0"
+git2 = { version = "0.20.2", default-features = false }
 ignore = "0.4.22"
 ratatui = "0.27.0"
 rayon = "1.10.0"
@@ -25,4 +25,4 @@ rayon = "1.10.0"
 [dev-dependencies]
 assert_cmd = "2.0"
 predicates = "3.1"
-tempfile = "3.10"
+tempfile = "3.10"