Revert "libraries: bump netty-tcnative version to 2.0.48"

This reverts commit de76c84.

This is to test whether this "fixes" the failing functional test
'xrootd-gsi-regression-test' on jenkins

pom.xml

@@ -434,7 +434,7 @@
             <dependency>
                 <groupId>io.netty</groupId>
                 <artifactId>netty-tcnative-boringssl-static</artifactId>
-                <version>2.0.48.Final</version>
+                <version>2.0.39.Final</version>
             </dependency>
             <dependency>
                 <groupId>com.sleepycat</groupId>