feat: support TS 4.4

[posva]

Fix #655

[codecov]

Codecov Report

Merging #656 (01c7a49) into v2 (dadb269) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##               v2     #656   +/-   ##
=======================================
  Coverage   96.67%   96.67%           
=======================================
  Files           9        9           
  Lines         361      361           
  Branches       96       96           
=======================================
  Hits          349      349           
  Misses          4        4           
  Partials        8        8           

Impacted Files	Coverage Δ
packages/pinia/src/store.ts	95.19% <ø> (ø)
packages/pinia/src/types.ts	100.00% <ø> (ø)

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