Release candidate v1.2.0-rc.0 (#2248)

Prepare for v1.2.0 with this release candidate.

To be merged after #2247 and #2246

Co-authored-by: Age Manning <Age@AgeManning.com>

common/lighthouse_version/src/lib.rs

@@ -16,7 +16,7 @@ pub const VERSION: &str = git_version!(
         // NOTE: using --match instead of --exclude for compatibility with old Git
         "--match=thiswillnevermatchlol"
     ],
-    prefix = "Lighthouse/v1.1.3-",
+    prefix = "Lighthouse/v1.2.0-rc.0-",
     fallback = "unknown"
 );