Remove tests flakyness

Tags/Categories only work on dates
and tests were assigning them randomly

test_site/content/posts/tutorials/devops/docker.md

@@ -1,6 +1,7 @@
 +++
 title = "Docker"
 order = 1
+date = "2017-01-01"
 +++
 
 A simple page

test_site/content/posts/tutorials/devops/nix.md

@@ -1,6 +1,7 @@
 +++
 title = "Nix"
 order = 2
+date = "2017-01-01"
 +++
 
 A simple page

test_site/content/posts/tutorials/programming/python.md

@@ -1,6 +1,7 @@
 +++
 title = "Python tutorial"
 order = 1
+date = "2017-01-01"
 +++
 
 A simple page

test_site/content/posts/tutorials/programming/rust.md

@@ -1,6 +1,7 @@
 +++
 title = "Rust"
 order = 2
+date = "2017-01-01"
 +++
 
 A simple page