Update legacy workflow to ubuntu-22.04

https://github.blog/changelog/2025-01-15-github-actions-ubuntu-20-runner-image-brownout-dates-and-other-breaking-changes/

Author: jdblischak

.github/workflows/legacy.yaml

@@ -5,7 +5,7 @@ on:
   workflow_dispatch:
 jobs:
   legacy:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     name: legacy
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
@@ -22,7 +22,6 @@ jobs:
       - name: Install system dependencies
         run: |
           sudo apt-get install -y software-properties-common
-          sudo add-apt-repository -y ppa:cran/libgit2
           sudo apt-get update
           sudo apt-get install -y \
             libcurl4-openssl-dev \
@@ -48,8 +47,8 @@ jobs:
         uses: actions/cache@v4
         with:
           path: ${{ env.R_LIBS_USER }}/*
-          key: ubuntu-20.04-${{ steps.install-r.outputs.installed-r-version }}-1-${{ hashFiles('DESCRIPTION') }}
-          restore-keys: ubuntu-20.04-${{ steps.install-r.outputs.installed-r-version }}-1-
+          key: ubuntu-22.04-${{ steps.install-r.outputs.installed-r-version }}-1-${{ hashFiles('DESCRIPTION') }}
+          restore-keys: ubuntu-22.04-${{ steps.install-r.outputs.installed-r-version }}-1-
       - name: Install dependencies
         run: Rscript scripts/install-legacy-versions.R
         working-directory: "workflowr-pkg-tests"

README.md

@@ -19,7 +19,7 @@ from GitHub
 Name    | OS           | R       | pandoc   | knitr   | rmarkdown | status
 ------- | ------------ | ------- | -------- | ------- | --------- | ------
 current | Ubuntu 22.04 | release | 2.16.2   | release | release   | [![current](https://github.com/workflowr/workflowr-pkg-tests/workflows/current/badge.svg)](https://github.com/workflowr/workflowr-pkg-tests/actions/workflows/current.yaml)
-legacy  | Ubuntu 20.04 | 3.3.3   | 1.19.2.4 | 1.29    | 1.18      | [![legacy](https://github.com/workflowr/workflowr-pkg-tests/workflows/legacy/badge.svg)](https://github.com/workflowr/workflowr-pkg-tests/actions/workflows/legacy.yaml)
+legacy  | Ubuntu 22.04 | 3.3.3   | 1.19.2.4 | 1.29    | 1.18      | [![legacy](https://github.com/workflowr/workflowr-pkg-tests/workflows/legacy/badge.svg)](https://github.com/workflowr/workflowr-pkg-tests/actions/workflows/legacy.yaml)
 future  | Ubuntu 24.04 | devel   | 2.19.2   | devel   | devel     | [![future](https://github.com/workflowr/workflowr-pkg-tests/workflows/future/badge.svg)](https://github.com/workflowr/workflowr-pkg-tests/actions/workflows/future.yaml)
 
 ## Monthly