Bump okhttp.version from 3.14.2 to 4.0.0 (#973)

Bumps `okhttp.version` from 3.14.2 to 4.0.0.

Updates `okhttp` and `mockwebserver` from 3.14.2 to 4.0.0.

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

Author: dependabot-preview[bot]

exonum-light-client/pom.xml

@@ -67,7 +67,7 @@
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <!-- Project dependencies -->
-    <okhttp.version>3.14.2</okhttp.version>
+    <okhttp.version>4.0.0</okhttp.version>
     <lombok.version>1.18.8</lombok.version>
     <!--Test dependencies-->
     <junit.jupiter.version>5.5.0</junit.jupiter.version>