diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index d00dc7a..21762ed 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -5,17 +5,13 @@ on: [push, pull_request]
 jobs:
   test:
     name: Run unit tests
-    strategy:
-      matrix:
-        go-version: [ 1.15.x ]
-        os: [ ubuntu-latest ]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
 
     steps:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: ${{ matrix.go-version }}
+          go-version: 1.19.x
 
       - name: Checkout code
         uses: actions/checkout@v3
diff --git a/.github/workflows/update.yml b/.github/workflows/update.yml
index bc36f13..f34aa60 100644
--- a/.github/workflows/update.yml
+++ b/.github/workflows/update.yml
@@ -10,7 +10,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: 1.15.x
+          go-version: 1.19.x
 
       - name: Checkout code
         uses: actions/checkout@v3
diff --git a/go.sum b/go.sum
index 0fb1fb6..3af10a9 100644
--- a/go.sum
+++ b/go.sum
@@ -1,24 +1,19 @@
-github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/leemcloughlin/jdn v0.0.0-20201102080031-6f88db6a6bf2 h1:CdyD5OzAIzNFzpJ9WQRjJWj4pVRxZ9v15xdHnhvUPdw=
 github.com/leemcloughlin/jdn v0.0.0-20201102080031-6f88db6a6bf2/go.mod h1:LAowglanJPLb6WYSx3D1Ht/XE54OGIr0i4mz9kdbXrs=
-github.com/mazznoer/csscolorparser v0.1.2 h1:/UBHuQg792ePmGFzTQAC9u+XbFr7/HzP/Gj70Phyz2A=
-github.com/mazznoer/csscolorparser v0.1.2/go.mod h1:Aj22+L/rYN/Y6bj3bYqO3N6g1dtdHtGfQ32xZ5PJQic=
 github.com/mazznoer/csscolorparser v0.1.3 h1:vug4zh6loQxAUxfU1DZEu70gTPufDPspamZlHAkKcxE=
 github.com/mazznoer/csscolorparser v0.1.3/go.mod h1:Aj22+L/rYN/Y6bj3bYqO3N6g1dtdHtGfQ32xZ5PJQic=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
-github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=