Release 5.0.5: bump vsn

[HJianBo]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 2887626468

• 2 of 3 (66.67%) changed or added relevant lines in 2 files are covered.
• 34 unchanged lines in 12 files lost coverage.
• Overall coverage decreased (-0.02%) to 78.897%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
apps/emqx_dashboard/src/emqx_dashboard_admin.erl	1	2	50.0%

Files with Coverage Reduction	New Missed Lines	%
apps/emqx_machine/src/emqx_machine.erl	1	79.31%
apps/emqx_management/src/emqx_mgmt_api_trace.erl	1	80.0%
apps/emqx_management/src/emqx_mgmt_util.erl	1	13.79%
apps/emqx/src/emqx_authentication_config.erl	1	84.75%
apps/emqx/src/emqx_router_utils.erl	1	58.14%
apps/emqx/src/persistent_session/emqx_persistent_session.erl	2	93.01%
apps/emqx_authn/src/emqx_authn.erl	3	77.78%
apps/emqx_gateway/src/exproto/emqx_exproto_gcli.erl	3	47.37%
apps/emqx/src/emqx_sys_mon.erl	4	86.46%
apps/emqx_management/src/emqx_mgmt_cli.erl	5	29.37%

Totals
Change from base Build 2887397027:	-0.02%
Covered Lines:	20985
Relevant Lines:	26598

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💛 - Coveralls