sqlx-macros-core: allow not calling cargo from a proc-macro#4315

lf- wants to merge 2 commits into

transact-rs:maintransact-rs/sqlx:mainfrom

MercuryTechnologies:jade/push-vwoyvrqvxpvzMercuryTechnologies/sqlx:jade/push-vwoyvrqvxpvzCopy head branch name to clipboard