Force rustup to install missing toolchain b/c it broke all of our builds

[atodorov]

From its changelog:
https://github.com/rust-lang/rustup/blob/master/CHANGELOG.md#1280---2025-03-04

rustup will no longer automatically install the active toolchain if it is not installed. pr#3985
To ensure its installation, run rustup toolchain install with no arguments.

Description of proposed changes

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Practical tips for PR review & merge:

• All GitHub Actions report PASS
• Newly added code/functions have unit tests
  • Coverage tools report all newly added lines as covered
  • The positive scenario is exercised
  • Negative scenarios are exercised, e.g. assert on all possible errors
  • Assert on events triggered if applicable
  • Assert on changes made to storage if applicable
• Modified behavior/functions - try to make sure above test items are covered
• Integration tests are added if applicable/needed

[github-actions]

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