Update libgit2 to 1.9 (#15018)

This is a routine update of libgit2 to 1.9.

libgit2 1.9 release notes:
https://github.com/libgit2/libgit2/releases/tag/v1.9.0
git2:
https://github.com/rust-lang/git2-rs/blob/master/CHANGELOG.md#0200---2025-01-04

Author: weihanglo

Cargo.lock

@@ -47,8 +47,8 @@ curl = "0.4.46"
 curl-sys = "0.4.73"
 filetime = "0.2.23"
 flate2 = { version = "1.0.30", default-features = false, features = ["zlib"] }
-git2 = "0.19.0"
-git2-curl = "0.20.0"
+git2 = "0.20.0"
+git2-curl = "0.21.0"
 gix = { version = "0.69.1", default-features = false, features = ["blocking-http-transport-curl", "progress-tree", "parallel", "dirwalk"] }
 glob = "0.3.1"
 handlebars = { version = "6.0.0", features = ["dir_source"] }
@@ -64,7 +64,7 @@ itertools = "0.14.0"
 jobserver = "0.1.32"
 lazycell = "1.3.0"
 libc = "0.2.155"
-libgit2-sys = "0.17.0"
+libgit2-sys = "0.18.0"
 libloading = "0.8.5"
 memchr = "2.7.4"
 miow = "0.6.0"