ci: set all runners to ubuntu-latest

It may be that ubuntu-latest breaks us, but we're not doing anything
particularly exotic so it seems unlikely.

Meanwhile, our use of ubuntu-20.04 HAS broken us, because that runner
is no longer supported.

Meanwhile also update a bunch of our action versions to v4, since some
of the v2s have become deprecated and removed. (Hopefully this won't
happen very often.)

Author: apoelstra

.github/workflows/fuzz.yml

@@ -11,7 +11,7 @@ on:
 jobs:
   fuzz:
     if: ${{ !github.event.act }}
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
@@ -28,8 +28,8 @@ roundtrip_semantic,
     steps:
       - name: Install test dependencies
         run: sudo apt-get update -y && sudo apt-get install -y binutils-dev libunwind8-dev libcurl4-openssl-dev libelf-dev libdw-dev cmake gcc libiberty-dev
-      - uses: actions/checkout@v2
-      - uses: actions/cache@v2
+      - uses: actions/checkout@v4
+      - uses: actions/cache@v4
         id: cache-fuzz
         with:
           path: |
@@ -45,7 +45,7 @@ roundtrip_semantic,
       - name: fuzz
         run: cd fuzz && ./fuzz.sh "${{ matrix.fuzz_target }}"
       - run: echo "${{ matrix.fuzz_target }}" >executed_${{ matrix.fuzz_target }}
-      - uses: actions/upload-artifact@v2
+      - uses: actions/upload-artifact@v4
         with:
           name: executed_${{ matrix.fuzz_target }}
           path: executed_${{ matrix.fuzz_target }}
@@ -55,8 +55,8 @@ roundtrip_semantic,
     needs: fuzz
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/download-artifact@v2
+      - uses: actions/checkout@v4
+      - uses: actions/download-artifact@v4
       - name: Display structure of downloaded files
         run: ls -R
       - run: find executed_* -type f -exec cat {} + | sort > executed

.github/workflows/rust.yml

@@ -4,7 +4,7 @@ name: Continuous integration
 
 jobs:
   Prepare:
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-latest
     outputs:
       nightly_version: ${{ steps.read_toolchain.outputs.nightly_version }}
     steps:
@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Crate
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Checkout Toolchain
         uses: actions-rs/toolchain@v1
         with:
@@ -45,7 +45,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Crate
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Checkout Toolchain
         uses: actions-rs/toolchain@v1
         with:
@@ -70,7 +70,7 @@ jobs:
           - rust: 1.48
     steps:
       - name: Checkout Crate
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Checkout Toolchain
         uses: actions-rs/toolchain@v1
         with:
@@ -88,7 +88,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Set up QEMU
         run: sudo apt update && sudo apt install -y qemu-system-arm gcc-arm-none-eabi
       - name: Checkout Toolchain