Bump com.guardsquare:proguard-gradle from 7.6.1 to 7.7.0

Bumps [com.guardsquare:proguard-gradle](https://github.com/Guardsquare/proguard) from 7.6.1 to 7.7.0.
- [Release notes](https://github.com/Guardsquare/proguard/releases)
- [Commits](Guardsquare/proguard@v7.6.1...v7.7)

---
updated-dependencies:
- dependency-name: com.guardsquare:proguard-gradle
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

build.gradle.kts

@@ -15,7 +15,7 @@ buildscript {
         google()
     }
     dependencies {
-        classpath("com.guardsquare:proguard-gradle:7.6.1")
+        classpath("com.guardsquare:proguard-gradle:7.7.0")
     }
 }
 val envProperties =  Properties()