Remove old CMake version (#1259)

The images used by github already come with a sufficiently recent CMake
version instead of a very outdated one. See:
https://github.com/actions/virtual-environments

Co-authored-by: friendlyanon <friendlyanon@users.noreply.github.com>

.github/workflows/ubuntu18-checkperf.yml

@@ -7,10 +7,6 @@ jobs:
     runs-on: ubuntu-18.04
     steps:
       - uses: actions/checkout@v2
-      - name: Setup cmake
-        uses: jwlawson/actions-setup-cmake@v1.0
-        with:
-          cmake-version: '3.9.x'
       - name: Use cmake
         run: |
           mkdir build &&

.github/workflows/ubuntu18.yml

@@ -7,10 +7,6 @@ jobs:
     runs-on: ubuntu-18.04
     steps:
       - uses: actions/checkout@v2
-      - name: Setup cmake
-        uses: jwlawson/actions-setup-cmake@v1.0
-        with:
-          cmake-version: '3.9.x'
       - name: Use cmake
         run: |
           mkdir build &&

.github/workflows/ubuntu20-checkperf.yml

@@ -7,10 +7,6 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
-      - name: Setup cmake
-        uses: jwlawson/actions-setup-cmake@v1.0
-        with:
-          cmake-version: '3.9.x'
       - name: Use cmake
         run: |
           mkdir build &&

.github/workflows/ubuntu20.yml

@@ -7,10 +7,6 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
-      - name: Setup cmake
-        uses: jwlawson/actions-setup-cmake@v1.0
-        with:
-          cmake-version: '3.9.x'
       - name: Use cmake
         run: |
           mkdir build &&