trie: remove use of deprecated setRoot

[acolytec3]

Small change to remove internal use of deprecated setRoot method in trie package

[codecov]

Codecov Report

Merging #1376 (0259fd4) into master (8b358df) will decrease coverage by 0.10%.
The diff coverage is n/a.

Flag	Coverage Δ
block	85.90% <ø> (ø)
blockchain	83.49% <ø> (ø)
client	83.70% <ø> (-0.32%)	⬇️
common	92.70% <ø> (-0.32%)	⬇️
devp2p	83.42% <ø> (+0.03%)	⬆️
ethash	82.83% <ø> (ø)
tx	88.24% <ø> (-0.12%)	⬇️
vm	79.31% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

[acolytec3]

While working in the baseTrie file, I noticed we were still using a deprecated setRoot method in some of our internal logic. I've updated the root setter to use the correct logic from setRoot and adjusted our internal usage accordingly so we're no longer using a deprecated method.

[ryanio]

lgtm!