Replace Travis env. variables with GitHub ones

Author: mortenpi

pdf/make.jl

@@ -40,8 +40,7 @@ end
 function makedocs(julia_exec)
     @sync begin
         builder = @async begin
-            withenv("TRAVIS_REPO_SLUG" => nothing, # workaround Documenter bugs and julia#26314
-                    "DOCUMENTER_KEY" => nothing, # skips deploydocs with the BuildBotConfig (see doc/make.jl)
+            withenv(DOCUMENTER_KEY" => nothing, # skips deploydocs with the BuildBotConfig (see doc/make.jl)
                     "BUILDROOT" => nothing) do
                 run(`make -C $(JULIA_SOURCE)/doc pdf texplatform=docker JULIA_EXECUTABLE=$(julia_exec)`)
             end
@@ -134,7 +133,7 @@ end
 
 # similar to Documenter.deploydocs
 function commit()
-    if get(ENV, "TRAVIS_PULL_REQUEST", "true") != "false"
+    if get(ENV, "GITHUB_EVENT_NAME", nothing) == "pull_request"
         @info "skipping commit from pull requests."
         return
     end