use vendored libgit2 without HTTPS / SSH support

we only read the repository so we don't need HTTPS and SSH support
dynamic linking causes headaches on NixOS which I use for hosting the treehouse

Cargo.lock

@@ -614,8 +614,6 @@ dependencies = [
  "libc",
  "libgit2-sys",
  "log",
- "openssl-probe",
- "openssl-sys",
  "url",
 ]
 
@@ -886,26 +884,10 @@ checksum = "10472326a8a6477c3c20a64547b0059e4b0d086869eee31e6d7da728a8eb7224"
 dependencies = [
  "cc",
  "libc",
- "libssh2-sys",
  "libz-sys",
- "openssl-sys",
  "pkg-config",
 ]
 
-[[package]]
-name = "libssh2-sys"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2dc8a030b787e2119a731f1951d6a773e2280c660f8ec4b0f5e1505a386e71ee"
-dependencies = [
- "cc",
- "libc",
- "libz-sys",
- "openssl-sys",
- "pkg-config",
- "vcpkg",
-]
-
 [[package]]
 name = "libz-sys"
 version = "1.1.20"
@@ -1007,24 +989,6 @@ version = "1.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3fdb12b2476b595f9358c5161aa467c2438859caa136dec86c26fdd2efe17b92"
 
-[[package]]
-name = "openssl-probe"
-version = "0.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ff011a302c396a5197692431fc1948019154afc178baf7d8e37367442a4601cf"
-
-[[package]]
-name = "openssl-sys"
-version = "0.9.103"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7f9e8deee91df40a943c71b917e5874b951d32a802526c85721ce3b776c929d6"
-dependencies = [
- "cc",
- "libc",
- "pkg-config",
- "vcpkg",
-]
-
 [[package]]
 name = "parking_lot"
 version = "0.12.2"

crates/treehouse/Cargo.toml

@@ -16,7 +16,7 @@ clap = { version = "4.3.22", features = ["derive"] }
 codespan-reporting = "0.11.1"
 copy_dir = "0.1.3"
 env_logger = "0.10.0"
-git2 = "0.19.0"
+git2 = { version = "0.19.0", default-features = false, features = ["vendored-libgit2"] }
 handlebars = "4.3.7"
 http-body = "1.0.0"
 image = "0.24.8"