Remove export of obsolete/removed package 'org.slf4j.impl' in OSGi

Since SLF4J 2 the connection between SLFJ4 and its providers is
established via the Service Loader mechanism, which is enabled in OSGi
runtimes using a Service Loader Mediator.

The package 'org.slf4j.impl' no longer exists in the logback-classic
bundle and therefore can not and need no longer be exported.

Fixes https://jira.qos.ch/browse/LOGBACK-1730

Signed-off-by: Hannes Wellmann <wellmann.hannes1@gmx.net>

logback-classic/pom.xml

@@ -314,7 +314,7 @@
         </executions>
         <configuration>
           <instructions>
-            <Export-Package>ch.qos.logback.classic*, org.slf4j.impl;version=${slf4j.version}</Export-Package>
+            <Export-Package>ch.qos.logback.classic*</Export-Package>
             <!-- LB-CLASSIC It is necessary to specify the rolling
                  file packages as classes are created via IOC (xml
                  config files). They won't be found by Bnd's analysis