Mavity Lib is a collection of code for modding without large amounts of setup.

To depend on Mavity Lib, use either cursemaven or modrinth maven.

To use cursemaven:
In your repositories block:

exclusiveContent {
    forRepository {
        maven {
            url "https://cursemaven.com"
        }
    }
    filter {
        includeGroup "curse.maven"
    }
}

To use Modrinth Maven:
In your repositories block:

  maven { url = "https://api.modrinth.com/maven" }

No matter which maven you use, also add the following to your repositories block:

  maven { url = "https://api.modrinth.com/maven" }
  maven { url = "https://maven.terraformersmc.com/releases/" }
  maven { url = "https://maven.ladysnake.org/releases" }
  maven { url = "https://mvn.devos.one/releases/" }

Now for actually adding the dependencies.

In your dependencies block:

  // Midnight Lib
  modImplementation "maven.modrinth:midnightlib:${project.midnightlib_version}"

  // Mod menu
  modImplementation("com.terraformersmc:modmenu:${project.mod_menu_version}") {
  	exclude group: "net.fabricmc.fabric-api"
  }

  // Trinkets
  modImplementation "dev.emi:trinkets:${project.trinkets_version}"

  // Pehkui
  modImplementation "com.github.Virtuoel:Pehkui:${project.pehkui_version}", {
  	exclude group: "net.fabricmc.fabric-api"
  }

  // Entity Hitboxes
  modImplementation "maven.modrinth:mecha-api:${project.mecha_api_version}"

  // Main Menu Credits
  modImplementation "maven.modrinth:main-menu-credits:${project.main_menu_credits_version}"

  // Porting Lib
  modImplementation "io.github.fabricators_of_create.Porting-Lib:${project.porting_lib_module}:${project.porting_lib_version}"

Then pick between the curse or modrinth maven.

  // Curse Maven Mavity Lib
  modImplementation "curse.maven:mavity_lib-1016352:${project.mavity_lib_version_curseforge}"

  // Modrinth Maven Mavity Lib
  modImplementation "maven.modrinth:mavity-lib:${project.mavity_lib_version_modrinth}"

And finally, in your gradle.properties:

mod_menu_version=7.0.1
mod_menu_version=7.0.1
trinkets_version=3.7.1
pehkui_version=3.8.0
midnightlib_version=1.4.1-fabric
mecha_api_version=0.1.0+1.20
porting_lib_version=2.3.4+1.20.1
porting_lib_module=obj_loader
main_menu_credits_version=1.1.2

# Do NOT use the sources jar. The default jar should deobfuscate properly.
mavity_lib_version_curseforge=5407783
mavity_lib_version_modrinth=5.0.2

(Also keeping in mind the values here will be the latest versions) But you can find all versions at either:
https://www.curseforge.com/minecraft/mc-mods/mavity-lib/files/all?page=1&pageSize=20
or https://modrinth.com/mod/mavity-lib/versions

Now you should be all ready to go on using Mavity Lib!