Bump gson from 2.8.7 to 2.8.8

Bumps [gson](https://github.com/google/gson) from 2.8.7 to 2.8.8.
- [Release notes](https://github.com/google/gson/releases)
- [Changelog](https://github.com/google/gson/blob/master/CHANGELOG.md)
- [Commits](https://github.com/google/gson/compare/gson-parent-2.8.7...gson-parent-2.8.8)

---
updated-dependencies:
- dependency-name: com.google.code.gson:gson
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

build.gradle

@@ -295,7 +295,7 @@ dependencies {
     implementation 'com.googlecode.ez-vcard:ez-vcard:0.11.2'
     implementation 'org.lukhnos:nnio:0.2'
     implementation 'org.bouncycastle:bcpkix-jdk15to18:1.69'
-    implementation 'com.google.code.gson:gson:2.8.7'
+    implementation 'com.google.code.gson:gson:2.8.8'
     implementation 'com.afollestad:sectioned-recyclerview:0.5.0'
     implementation 'com.github.chrisbanes:PhotoView:2.3.0'
     implementation 'pl.droidsonroids.gif:android-gif-drawable:1.2.21'