build: Update last 2 libraries that used JCenter

Both of these are present in mavenCentral with a different groupId.

For both of them, the version bump is only for the groupId change, there are no breaking changes otherwise.

Signed-off-by: Álvaro Brey Vilas <alvaro.brey@nextcloud.com>

app/build.gradle

@@ -241,7 +241,7 @@ dependencies {
     implementation 'com.github.chrisbanes:PhotoView:2.3.0'
     implementation 'pl.droidsonroids.gif:android-gif-drawable:1.2.24'
     implementation 'com.github.tobiaskaminsky:qrcodescanner:0.1.2.4' // 'com.github.blikoon:QRCodeScanner:0.1.2'
-    implementation 'com.google.android:flexbox:2.0.1'
+    implementation 'com.google.android.flexbox:flexbox:3.0.0'
     implementation('com.github.bumptech.glide:glide:3.8.0') {
         exclude group: "com.android.support"
     }
@@ -275,7 +275,7 @@ dependencies {
     implementation 'com.simplecityapps:recyclerview-fastscroll:2.0.1'
     
     // Shimmer animation
-    implementation 'com.elyeproj.libraries:loaderviewlibrary:2.0.0'
+    implementation 'io.github.elye:loaderviewlibrary:3.0.0'
 
     // dependencies for markdown rendering
     implementation "io.noties.markwon:core:$markwonVersion"

build.gradle

@@ -34,7 +34,6 @@ subprojects {
     repositories {
         google()
         mavenCentral()
-        jcenter()
         maven { url "https://jitpack.io" }
     }
 }