Added Store.getsize #1831

Job	Run time
py=3.11-min_deps	3m 21s
os=ubuntu-latest, py=3.11, np=1.25, deps=minimal	2m 22s
py=3.13-upstream	4m 6s
os=ubuntu-latest, py=3.11, np=1.25, deps=optional	2m 26s
os=ubuntu-latest, py=3.11, np=2.1, deps=minimal	2m 20s
os=ubuntu-latest, py=3.11, np=2.1, deps=optional	2m 16s
os=ubuntu-latest, py=3.12, np=1.25, deps=minimal	2m 26s
os=ubuntu-latest, py=3.12, np=1.25, deps=optional	2m 43s
os=ubuntu-latest, py=3.12, np=2.1, deps=minimal	2m 23s
os=ubuntu-latest, py=3.12, np=2.1, deps=optional	2m 24s
os=ubuntu-latest, py=3.13, np=1.25, deps=minimal	5m 13s
os=ubuntu-latest, py=3.13, np=1.25, deps=optional	4m 33s
os=ubuntu-latest, py=3.13, np=2.1, deps=minimal	2m 36s
os=ubuntu-latest, py=3.13, np=2.1, deps=optional	2m 28s
os=macos-latest, py=3.11, np=1.25, deps=optional	1m 44s
os=macos-latest, py=3.13, np=2.1, deps=optional	2m 5s
	45m 26s

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