Modernize runtime dependencies (beam-community#249)

* Modernize versions

* Exclude elixir 1.12 on OTP 21

* Update ci.yml

* Update mix.exs

* Remove unused directory

* Create dependabot.yml

.github/dependabot.yml

@@ -0,0 +1,7 @@
+version: 2
+updates:
+- package-ecosystem: mix
+  directory: "/"
+  schedule:
+    interval: weekly
+  open-pull-requests-limit: 999

.github/workflows/ci.yml

@@ -15,10 +15,12 @@ jobs:
     name: Test (OTP ${{matrix.otp}} / Elixir ${{matrix.elixir}})
     strategy:
       matrix:
-        elixir: ['1.10', '1.9', '1.8', '1.7']
+        elixir: ['1.12', '1.11', '1.10', '1.9']
         # All of the above can use this version. For details see: https://hexdocs.pm/elixir/compatibility-and-deprecations.html#compatibility-between-elixir-and-erlang-otp
-        otp: [22, 21]
-
+        otp: [24, 23, 22, 21]
+        exclude:
+          - {otp: '21', elixir: '1.12'}
+          - {otp: '24', elixir: '1.9'}
     steps:
       - uses: actions/checkout@v2
       - uses: erlef/setup-beam@v1
@@ -33,9 +35,9 @@ jobs:
     name: Linting
     strategy:
       matrix:
-        elixir: ['1.10']
+        elixir: ['1.12']
         # All of the above can use this version. For details see: https://hexdocs.pm/elixir/compatibility-and-deprecations.html#compatibility-between-elixir-and-erlang-otp
-        otp: [22, 21]
+        otp: [24]
     steps:
       - uses: actions/checkout@v2
       - uses: erlef/setup-beam@v1

mix.exs

@@ -8,7 +8,7 @@ defmodule JSONAPI.Mixfile do
       package: package(),
       compilers: compilers(Mix.env()),
       description: description(),
-      elixir: "~> 1.7",
+      elixir: "~> 1.9",
       elixirc_paths: elixirc_paths(Mix.env()),
       build_embedded: Mix.env() == :prod,
       start_permanent: Mix.env() == :prod,