use elixir 1.14 for mixed version archive

Author: HoloRin

.github/workflows/templates/test-mixed-versions.template.yaml

@@ -94,7 +94,7 @@ jobs:
       uses: erlef/[email protected]
       with:
         otp-version: ${{ steps.check.outputs.otp_version }}
-        elixir-version: 1.15
+        elixir-version: 1.14
         hexpm-mirrors: |
           https://builds.hex.pm
           https://cdn.jsdelivr.net/hex

.github/workflows/test-mixed-versions.yaml

@@ -72,7 +72,7 @@ jobs:
       uses: erlef/[email protected]
       with:
         otp-version: ${{ steps.check.outputs.otp_version }}
-        elixir-version: 1.15
+        elixir-version: 1.14
         hexpm-mirrors: |
           https://builds.hex.pm
           https://cdn.jsdelivr.net/hex