Allow building signed app using GitLab CI

app/build.gradle

@@ -7,10 +7,6 @@ plugins {
     id 'org.jetbrains.kotlin.plugin.serialization'
 }
 
-def keystorePropertiesFile = rootProject.file("keystore.properties")
-def keystoreProperties = new Properties()
-keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
-
 android {
     compileSdk 31
 
@@ -24,10 +20,19 @@ android {
 
     signingConfigs {
         release {
-            keyAlias keystoreProperties['keyAlias']
-            keyPassword keystoreProperties['keyPassword']
-            storeFile file(keystoreProperties['storeFile'])
-            storePassword keystoreProperties['storePassword']
+            file("../keystore.properties").with { keystorePropertiesFile ->
+                if (keystorePropertiesFile.canRead()) {
+                    def keystoreProperties = new Properties()
+                    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
+
+                    keyAlias keystoreProperties['keyAlias']
+                    keyPassword keystoreProperties['keyPassword']
+                    storeFile file(keystoreProperties['storeFile'])
+                    storePassword keystoreProperties['storePassword']
+                } else {
+                    println 'Unable to read keystore.properties'
+                }
+            }
         }
     }