package.json: start v0.28.0-dev

v0.28.0 will require VS Code API 1.59 or newer
(VS Code July release)

Updates golang/vscode-go#1659

Change-Id: I0a83e2f1b3459f18d7b3f752210e3c1ea07a3d39
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/340849
Trust: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Suzy Mueller <suzmue@golang.org>
diff --git a/package-lock.json b/package-lock.json
index a4fc7b5..986ef63 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "go",
-  "version": "0.27.0-dev",
+  "version": "0.28.0-dev",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "go",
-      "version": "0.26.0-dev",
+      "version": "0.28.0-dev",
       "license": "MIT",
       "dependencies": {
         "deep-equal": "^2.0.2",
@@ -49,7 +49,7 @@
         "yarn": "^1.22.4"
       },
       "engines": {
-        "vscode": "^1.52.0"
+        "vscode": "^1.59.0"
       }
     },
     "node_modules/@babel/code-frame": {