Update libgit2 dependency

.gitmodules

@@ -1,4 +1,4 @@
 [submodule "deps/libgit2"]
 	path = deps/libgit2
 	url = https://github.com/libgit2/libgit2.git
-	ignore = untracked
+	branch = maint/v0.28

.travis.yml

@@ -5,15 +5,12 @@ notifications:
     on_success: never
     on_failure: change
 
-node_js: "10"
+node_js: "12"
 
 git:
   depth: 10
   submodules: false
 
-before_install:
-  - git submodule update --init
-
 branches:
   only:
     - master
@@ -22,3 +19,11 @@ sudo: false
 
 env:
   - CC=clang CXX=clang++ npm_config_clang=1
+
+install:
+  - npm run prepare
+  - npm install
+
+script:
+  - npm run lint
+  - npm run test

README.md

@@ -10,9 +10,9 @@ Helpers for working with Git repositories built natively on top of
 npm install git-utils
 ```
 
-## Building
-  * Clone the repository with the `--recurse` option to get the libgit2
-    submodule
+## Development
+  * Clone the repository
+  * Run `npm run prepare` to get the submodule
   * Run `npm install`
   * Run `npm test` to run the specs
 

appveyor.yml

@@ -1,5 +1,7 @@
 version: "{build}"
 
+image: Visual Studio 2015
+
 platform: x64
 
 branches:
@@ -11,11 +13,12 @@ clone_depth: 10
 skip_tags: true
 
 install:
-  - git submodule update --init
-  - ps: Install-Product node 6
+  - ps: Install-Product node 12
+  - npm run prepare
   - npm install
+  - npm run lint
+  - npm run test
 
 build: off
 test: off
 deploy: off
-