github: bump to ubuntu 22.04

This should get the aya integration tests passing, which are not yet
able to run on older kernels. See aya-rs/aya#725
and aya-rs/aya#638.

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
     uses: ./.github/workflows/llvm.yml
 
   lint-stable:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
 
     steps:
       - uses: actions/checkout@v3
@@ -34,7 +34,7 @@ jobs:
         run: cargo clippy --features llvm-sys/no-llvm-linking --all-targets --workspace -- --deny warnings
 
   lint-nightly:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
 
     steps:
       - uses: actions/checkout@v3
@@ -48,7 +48,7 @@ jobs:
         run: cargo fmt --all -- --check
 
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:
@@ -91,11 +91,16 @@ jobs:
 
       - name: Install dependencies
         if: matrix.rust == 'nightly'
-        # ubuntu-20.04 comes with clang prior to
-        # https://github.com/llvm/llvm-project/commit/6d6750696400 which does not implement
-        # __builtin_preserve_enum_value, used by relocation tests in aya.
+        # ubuntu-22.04 comes with clang 14[0] which doesn't include support for signed and 64bit
+        # enum values which was added in clang 15[1].
         #
         # gcc-multilib provides at least <asm/types.h> which is referenced by libbpf.
+        #
+        # llvm provides llvm-objcopy which is used to build the BTF relocation tests.
+        #
+        # [0] https://github.com/actions/runner-images/blob/ubuntu22/20230724.1/images/linux/Ubuntu2204-Readme.md
+        #
+        # [1] https://github.com/llvm/llvm-project/commit/dc1c43d
         run: |
           set -euxo pipefail
           wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -

.github/workflows/llvm.yml

@@ -8,7 +8,7 @@ on:
 
 jobs:
   llvm:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     name: llvm
     outputs:
       cache-key: ${{ steps.cache-key.outputs.cache-key }}

.github/workflows/release.yml

@@ -10,7 +10,7 @@ jobs:
 
   upload-bins:
     # TODO: Build for macos someday.
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     needs: llvm
     steps:
       - name: Restore LLVM