cargo-install-all: use full path for sourcing

[CriesofCarrots]

Problem

scripts/cargo-install-all.sh breaks when run outside the solana directory: https://discord.com/channels/428295358100013066/670512312339398668/1186583553325142077
This is because source isn't handling the relative path to spl-token-cli-version.sh correctly

Summary of Changes

Use full path instead

[mergify]

Backports to the stable branch are to be avoided unless absolutely necessary for fixing bugs, security issues, and perf regressions. Changes intended for backport should be structured such that a minimum effective diff can be committed separately from any refactoring, plumbing, cleanup, etc that are not strictly necessary to achieve the goal. Any of the latter should go only into master and ride the normal stabilization schedule.

[mergify]

Backports to the beta branch are to be avoided unless absolutely necessary for fixing bugs, security issues, and perf regressions. Changes intended for backport should be structured such that a minimum effective diff can be committed separately from any refactoring, plumbing, cleanup, etc that are not strictly necessary to achieve the goal. Any of the latter should go only into master and ride the normal stabilization schedule. Exceptions include CI/metrics changes, CLI improvements and documentation updates on a case by case basis.

[willhickey]