support 1.6 LTS

Author: mykelk

Diff for: .github/workflows/CI.yml

@@ -17,7 +17,7 @@ jobs:
       fail-fast: false
       matrix:
         version:
-          - "1.0"  # LTS
+          - "1.6"  # LTS
           - "1"    # Latest Release
         os:
           - ubuntu-latest

Diff for: Project.toml

@@ -13,7 +13,7 @@ CommonSubexpressions = "0.2, 0.3"
 Graphs = "1.4, 1.5, 1.6, 1.7, 1.8, 1.9"
 MacroTools = "0.4, 0.5"
 TikzGraphs = "1.3, 1.4"
-julia = "1"
+julia = "1.6"
 
 [extras]
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"