Github actions go test cannot find package error. How can I fix this?

I have a simple go package, but during testing within Github Actions, it is failing with this error:

##[error]keywords.go:8:2: cannot find package "github.com/securisec/go-keywords/languages" in any of:.

When I run the tests locally (I am using go mod), all the tests works fine.

For Github actions, I have tried setting GO111MODULE to both on and off, but still getting the same error.

The error can be observed here. My testing workflow is:

name: tests

on:
  - push
  - pull_request

jobs:
  test:
    name: Test package
    strategy:
      max-parallel: 3
      fail-fast: false
      matrix:
        os:
          - ubuntu-latest
        go:
          - "1.11"
          - "1.13"
          - "1.14"
    runs-on: ${{ matrix.os }}
    steps:
      - name: Checkout
        uses: actions/checkout@v2
        env:
          GOPATH: ${{ runner.workspace }}
          GO111MODULE: "on"

      - name: Go setup
        uses: actions/setup-go@v1.0.0
        with:
          go-version: ${{matrix.go}}
        env:
          GOPATH: ${{ runner.workspace }}
          GO111MODULE: "on"
      - name: Run test
        env:
          GOPATH: ${{ runner.workspace }}
          GO111MODULE: "on"
        run: |
          go get -u github.com/grokify/html-strip-tags-go
          go test ./...
      - if: failure()
        run: ls -R

Go mod file:

module github.com/securisec/go-keywords

go 1.14

require github.com/grokify/html-strip-tags-go v0.0.0-20200322061010-ea0c1cf2f119

How can I fix this error?