chore: add codemeta.json

Used the template from the codemeta repository and modified it to suit
the project. This file also tracks the version, and must be updated when
other versions in the project are bumped.

codemeta.json

@@ -0,0 +1,65 @@
+{
+  "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
+  "@type": "SoftwareSourceCode",
+  "identifier": "gradus",
+  "description": "Extensible spacetime agnostic general relativistic ray-tracing (GRRT): Gradus.jl is a suite of tools related to tracing geodesics and calculating observational signatures of accreting compact objects. Gradus.jl requires only a specification of the non-zero metric components of a chosen spacetime in order to solve the geodesic equation and compute a wide variety of trajectories and orbits. Various algorithms for calculating physical quantities are implemented generically, so they may be used with different classes of spacetime with minimal implementation.",
+  "name": "Gradus.jl",
+  "codeRepository": "https://github.com/astro-group-bristol/Gradus.jl",
+  "issueTracker": "https://github.com/astro-group-bristol/Gradus.jl/issues",
+  "license": "https://spdx.org/licenses/GPL-3.0",
+  "version": "0.4.26",
+  "programmingLanguage": {
+    "@type": "ComputerLanguage",
+    "name": "Julia",
+    "url": "https://julialang.org/"
+  },
+  "author": [
+    {
+      "@type": "Person",
+      "givenName": "Fergus",
+      "familyName": "Baker",
+      "email": "fergus.baker@bristol.ac.uk"
+    },
+    {
+      "@type": "Person",
+      "givenName": "Andy",
+      "familyName": "Young",
+      "email": "Andy.Young@bristol.ac.uk"
+    }
+  ],
+  "contributor": [
+    {
+      "@type": "Person",
+      "givenName": "Wiktoria",
+      "familyName": "Tarnopolska"
+    }
+  ],
+  "copyrightHolder": [
+    {
+      "@type": "Person",
+      "givenName": "Fergus",
+      "familyName": "Baker",
+      "email": "fergus.baker@bristol.ac.uk"
+    }
+  ],
+  "maintainer": [
+    {
+      "@type": "Person",
+      "givenName": "Fergus",
+      "familyName": "Baker",
+      "email": "fergus.baker@bristol.ac.uk"
+    }
+  ],
+  "softwareRequirements": {
+    "1": {
+      "@type": "SoftwareApplication",
+      "identifier": "julia",
+      "name": "Julia",
+      "version": ">= 1.11.0"
+    },
+    "SystemRequirements": null
+  },
+  "keywords": ["astrophysics", "general-relativity", "black-holes", "ray-tracing", "grrt", "gravity", "simulation"],
+  "readme": "https://github.com/astro-group-bristol/Gradus.jl/blob/main/README.md"
+}
+