[feature] refresh credentials after x hours

[dennisvandevenne]

Getting credentials each time from AWS is slow, we could keep credentials for a specified time (which is maximum less than the credential rotation overlap)

Notes:

• First idea was to use pool, but sometimes this gave 502. test, minDB
• FYI, I now get the creds daily from ASW and save them locally and connect per query. That works too and is fast enough... but is less elegant.