Switch ostree source to git

rust-bindings/rust/Makefile

@@ -1,7 +1,8 @@
 GIR_REPO := https://github.com/gtk-rs/gir.git
 GIR_VERSION := 2d1ffab19eb5f9a2f0d7a294dbf07517dab4d989
+OSTREE_REPO := https://github.com/ostreedev/ostree
+OSTREE_VERSION := v2020.4
 RUSTDOC_STRIPPER_VERSION := 0.1.13
-OSTREE_VER := 2020.4
 
 all: gir
 
@@ -49,7 +50,9 @@ gir-files:
 
 gir-files/OSTree-1.0.gir:
 	podman build \
-		--build-arg OSTREE_VER=$(OSTREE_VER) \
+		--pull \
+		--build-arg OSTREE_REPO=$(OSTREE_REPO) \
+		--build-arg OSTREE_VERSION=$(OSTREE_VERSION) \
 		-t ostree-build \
 		.
 	podman run \