Remove the legacy builders (#776)

These builds are no longer working because some of the dependencies now
require newer versions of Go. Seems like the ecosystem has moved to Go
1.11+, so we are now forced to follow suit.

.github/workflows/ci.yml

@@ -9,45 +9,11 @@ on:
 
 jobs:
 
-  build-legacy:
-    strategy:
-      fail-fast: false
-      matrix:
-        go: [ '1.9', '1.10' ]
-    name: Go ${{ matrix.go }}
-
-    runs-on: ubuntu-18.04
-
-    steps:
-    - name: Set up Go
-      uses: actions/setup-go@v1
-      with:
-        go-version: ${{ matrix.go }}
-      id: go
-    - name: Check out code into the GOPATH
-      uses: actions/checkout@v1
-      with:
-        fetch-depth: 1
-        path: src/github.com/${{ github.repository }}
-    - name: Build
-      env:
-        GOPATH: /home/runner/work/git2go
-      run: |
-        git submodule update --init
-        sudo apt-get install -y --no-install-recommends libssh2-1-dev
-        make build-libgit2-static
-        go get -tags static -t github.com/${{ github.repository }}/...
-        go build -tags static github.com/${{ github.repository }}/...
-    - name: Test
-      env:
-        GOPATH: /home/runner/work/git2go
-      run: make TEST_ARGS=-test.v test-static
-
   build-static:
     strategy:
       fail-fast: false
       matrix:
-        go: [ '1.11', '1.12', '1.13', '1.14', '1.15' ]
+        go: [ '1.11', '1.12', '1.13', '1.14', '1.15', '1.16', '1.17' ]
     name: Go ${{ matrix.go }}
 
     runs-on: ubuntu-20.04