CI: update GHA instances from Ubuntu 18.04 to 20.04

The release binaries are built using Ubuntu 18.04 in Docker on Ubuntu 20.04
for glibc compatibility reason (issue 7255).

Fix issue 7297

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

.github/workflows/ci.yml

@@ -25,9 +25,15 @@ jobs:
 
     strategy:
       matrix:
-        os: [ubuntu-18.04, macos-12, windows-2019]
+        os: [ubuntu-20.04, macos-12, windows-2019]
 
     steps:
+      - name: Install dependencies
+        if: matrix.os == 'ubuntu-20.04'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libbtrfs-dev
+
       - uses: actions/setup-go@v3
         with:
           go-version: ${{ env.GO_VERSION }}
@@ -44,7 +50,7 @@ jobs:
   #
   project:
     name: Project Checks
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     timeout-minutes: 5
 
     steps:
@@ -72,7 +78,7 @@ jobs:
   #
   protos:
     name: Protobuf
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     timeout-minutes: 5
 
     defaults:
@@ -108,7 +114,7 @@ jobs:
 
   man:
     name: Manpages
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     timeout-minutes: 5
 
     steps:
@@ -218,9 +224,15 @@ jobs:
 
     strategy:
       matrix:
-        os: [ubuntu-18.04, macos-12, windows-2019, windows-2022]
+        os: [ubuntu-20.04, macos-12, windows-2019, windows-2022]
         go-version: ["1.19.2", "1.18.7"]
     steps:
+      - name: Install dependencies
+        if: matrix.os == 'ubuntu-20.04'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libbtrfs-dev
+
       - uses: actions/setup-go@v3
         with:
           go-version: ${{ matrix.go-version }}
@@ -402,7 +414,7 @@ jobs:
 
   integration-linux:
     name: Linux Integration
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     timeout-minutes: 40
     needs: [project, linters, protos, man]
 
@@ -436,7 +448,7 @@ jobs:
         env:
           RUNC_FLAVOR: ${{ matrix.runc }}
         run: |
-          sudo apt-get install -y gperf
+          sudo apt-get install -y gperf libbtrfs-dev
           script/setup/install-seccomp
           script/setup/install-runc
           script/setup/install-cni $(grep containernetworking/plugins go.mod | awk '{print $2}')