build: Load keystore file from rootProject

Since the signing config is also stored in the project root it makes sense to have storeFile
path be relative to it.

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

ui/build.gradle

@@ -41,7 +41,7 @@ android {
             release {
                 keyAlias keystoreProperties['keyAlias']
                 keyPassword keystoreProperties['keyPassword']
-                storeFile file(keystoreProperties['storeFile'])
+                storeFile rootProject.file(keystoreProperties['storeFile'])
                 storePassword keystoreProperties['storePassword']
             }
         }