chore: switch from ctest to ctest2

ctest is nearly unmaintained and emits lots of warnings.
Switch to ctest2 to fix those.

Author: weihanglo

systest/Cargo.toml

@@ -10,4 +10,4 @@ libgit2-sys = { path = "../libgit2-sys", features = ['https', 'ssh'] }
 libc = "0.2"
 
 [build-dependencies]
-ctest = "0.2.17"
+ctest2 = "0.4"

systest/build.rs

@@ -2,7 +2,7 @@ use std::env;
 use std::path::PathBuf;
 
 fn main() {
-    let mut cfg = ctest::TestGenerator::new();
+    let mut cfg = ctest2::TestGenerator::new();
     if let Some(root) = env::var_os("DEP_GIT2_ROOT") {
         cfg.include(PathBuf::from(root).join("include"));
     }