Add empty exclusion list for incremental builds

The default exclusion list from apache/camel contains modules that don't exist
in camel-spring-boot (like :camel-allcomponents, :dummy-component, etc.), which
causes Maven to fail with 'Could not find the selected project in the reactor'.

This empty exclusion list overrides the defaults and allows incremental builds
to work correctly.

Author: cunningt

.github/actions/incremental-build/exclusions.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+# Exclusion list for camel-spring-boot incremental builds
+# Override the default exclusion list from apache/camel which contains modules
+# that don't exist in camel-spring-boot
+
+# camel-spring-boot has fewer generated/meta modules to exclude
+# Most exclusions from main Camel don't apply here
+EXCLUSION_LIST=""