Merge rust-bitcoin#4188: ci: update Kani GitHub Actions runners to ubuntu-24.04

e3f409e ci: update Kani GitHub Actions runners to ubuntu-24.04 (Erick Cestari)

Pull request description:

  GitHub is deprecating the ubuntu-20.04 runner, with removal scheduled for 2025-04-01 (see [GitHub Issue #11101](actions/runner-images#11101)).

  This PR updates the CI/CD workflows to use ubuntu-24.04 instead of ubuntu-20.04 for the following workflows:

  - cron-daily-kani.yml
  - rust.yml (Kani codegen job)

  This change should resolve the CI/CD error in the Kani codegen - stable toolchain job triggered by pull requests.

ACKs for top commit:
  Kixunil:
    ACK e3f409e
  apoelstra:
    ACK e3f409e; successfully ran local tests

Tree-SHA512: 7e235b68226042937e7269cccae4850cd33cc09c1546a068542903bf9756aaf77155fce3991f899b8470bc97a7115c7ed22e4f09a4c4f4061897a0b18a993487

Author: apoelstra

.github/workflows/cron-daily-kani.yml

@@ -5,7 +5,7 @@ on:
     - cron: '59 23 * * *'       # midnight every day.
 jobs:
   run-kani:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
       - name: 'Checkout your code.'
         uses: actions/checkout@v4

.github/workflows/rust.yml

@@ -296,7 +296,7 @@ jobs:
 
   Kani:
     name: Kani codegen - stable toolchain
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
       - name: "Checkout repo"
         uses: actions/checkout@v4