Update git submodules

Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to 5376a65d586b37f13342f9e108f224b73d4149fc
  - Merge "SO API extenstion to retrieve all PNF workflow"
  - SO API extenstion to retrieve all PNF workflow

    This commit implements SO request handler API
    onap/so/infra/workflowSpecifications/v[x]/pnfWorkFlows.
    It is used to get all the pnf workflows exist in
    catalogdb.

    Issue-ID: SO-2660
    Change-Id: Ieeca8a6afef917b6e3ba927d38ed5509dcaf253c
    Signed-off-by: tragait <rahul.tyagi@est.tech>