As of end of 2018, there's still no forge for Minecraft 1.13, I decided to give the new modloader Rift a try, and ported Durabilityviewer over.
Rift is, by far, not as complete as Forge - it's harder to install, and it lacks features like a general options screen to configure mods, so expect some clumsyness. Also, this is for 1.13.2 only, and I'm currently not planning to make the durability viewer available to 1.13 or 1.13.1.
First, you need to install Rift 1.0.4-77 for 1.13.2 from https://jitpack.io/com/github/Chocohead/Rift/jitpack-SNAPSHOT/Rift-jitpack-SNAPSHOT.jar. Don't use the version from curseforge, it's for 1.13, not 1.13.2.
According to the docs, double-clicking the jar file should copy it to where it should be, then create a new launcher profile. (As I'm using MultiMC, I didn't test that).
For MultiMC, follow the video at https://www.youtube.com/watch?v=y_4BlbBXEHI, this is what I did to get it to work.
Next, download the Durability viewer jar, and put it into your .minecraft/mods folder.
I implemented a config GUI for my mods that uses the resource pack list where Rift puts all its mods. Go to Options/Resource Packs, hover the mouse over the mod image, and click the book that shows. The hotkey can be configured in Options/Controls as usual.