Fix a dependency error for release builds.(LeakCanary)

[DenBond7]

@DenBond7 No, it eventually fails:

$ ./gradlew clean assemble

.....

> Task :FlowCrypt:compileConsumerReleaseKotlin FAILED
e: /home/ivan/pro/flowcrypt/flowcrypt-android/FlowCrypt/src/main/java/com/flowcrypt/email/FlowCryptApplication.kt: (27, 8): Unresolved reference: leakcanary
e: /home/ivan/pro/flowcrypt/flowcrypt-android/FlowCrypt/src/main/java/com/flowcrypt/email/FlowCryptApplication.kt: (123, 7): Unresolved reference: LeakCanary
e: /home/ivan/pro/flowcrypt/flowcrypt-android/FlowCrypt/src/main/java/com/flowcrypt/email/FlowCryptApplication.kt: (123, 18): Variable expected
e: /home/ivan/pro/flowcrypt/flowcrypt-android/FlowCrypt/src/main/java/com/flowcrypt/email/FlowCryptApplication.kt: (123, 27): Unresolved reference: LeakCanary
e: /home/ivan/pro/flowcrypt/flowcrypt-android/FlowCrypt/src/main/java/com/flowcrypt/email/FlowCryptApplication.kt: (124, 7): Unresolved reference: LeakCanary

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':FlowCrypt:compileConsumerReleaseKotlin'.
> Compilation error. See log for more details

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 3m 4s
67 actionable tasks: 30 executed, 37 from cache

Originally posted by @IvanPizhenko in #1102 (comment)