(PUP-2889) Bump win32-eventlog dependency to ~> 0.6.1

Previously, the x86 version of the puppet gem depended on win32-eventlog
~> 0.5.3 which is not ffi compatible. This was caused when eventlog
changes were reverted in 35b1abc1, and then reimplemented in
537b0572, but the corresponding eventlog dependency was not bumped.

This commit bumps the dependency to use ~> 0.6.1 for x86. The x64
version already correctly depends on ~> 0.6.1.