Build: Add .npmrc with save-exact=true

This makes commands like `npm install package --save-dev` always get saved
to package.json as a pinned version and not as a `^`-delimited range.

(cherry-picked from 6600e2e2b9863dc91601d94541a3808cf3ccc90c)

diff --git a/.npmrc b/.npmrc
new file mode 100644 (file)
index 0000000..cffe8cd
--- /dev/null
+++ b/.npmrc
@@ -0,0 +1 @@
+save-exact=true