Update build version to 1.2.0 (#3016)

**What type of PR is this?**
> Uncomment only one ` /kind` line, and delete the rest.
> For example, `> /kind bug` would simply become: `/kind bug`

/kind feature

**What does does this PR do / why we need it**:

Updates the build version to 1.2.0

**Which issue(s) this PR fixes**:

N/A

**How to test changes / Special notes to the reviewer**:

N/A

Signed-off-by: Charlie Drage <charlie@charliedrage.com>

build/VERSION

@@ -1 +1 @@
-v1.1.3
+v1.2.0