[lldb] Update TestDump.test for gnuwin32's 'file' command output

Remove the colon from the CHECK line for the output of the file command.
On macOS and Linux, the file command uses a colon as the separator
between the path and the file type, but gnuwin32's file command uses a
semicolon.

Author: JDevlieghere

lldb/test/Shell/Diagnostics/TestDump.test

@@ -12,4 +12,4 @@
 # RUN: %lldb -o 'diagnostics dump -d %t.nonexisting'
 # RUN: file %t.nonexisting | FileCheck %s
 
-# CHECK: : directory
+# CHECK: directory