v0.6.4

ITensors v0.6.4

Diff since v0.6.3

Merged pull requests:

• [SparseArrayDOKs] Add setindex_maybe_grow! and macro @maybe_grow (#1434) (@emstoudenmire)
• [ITensorMPS] Allow customizing apply (#1440) (@mtfishman)

Closed issues:

• [SparseArrayDOKs] [ENHANCEMENT] resize! and @maybe_grow (#1433)