CondaPkg only supports Julia 1.6 upwards

Author: Christopher Doris

.github/workflows/tests.yml

@@ -69,10 +69,7 @@ jobs:
       matrix:
         arch: [x64] # x86 unsupported by MicroMamba
         os: [ubuntu-latest, windows-latest, macos-latest]
-        jlversion: ['1','1.6','1.5','1.4'] # 1.3 unsupported by MicroMamba
-        exclude:
-        - os: macos-latest
-          arch: x86
+        jlversion: ['1','1.6']
     steps:
       - uses: actions/checkout@v2
       - uses: julia-actions/setup-julia@v1