Apply suggestions from code review

Author: DanielDoehring

Project.toml

@@ -25,7 +25,6 @@ MPI = "da04e1cc-30fd-572f-bb4f-1f8673147195"
 MuladdMacro = "46d2c3a1-f734-5fdb-9937-b9b9aeba4221"
 Octavian = "6fd5a793-0b7e-452c-907f-f8bfe9c57db4"
 OffsetArrays = "6fe1bfb0-de20-5000-8ca7-80f57d26f881"
-OrdinaryDiffEqSDIRK = "2d112036-d095-4a1e-ab9a-08536f3ecdbf"
 P4est = "7d669430-f675-4ae7-b43e-fab78ec5a902"
 Polyester = "f517fe37-dbe3-4b94-8317-1923a5111588"
 PrecompileTools = "aea7be01-6a6a-4083-8856-8a6e6704d82a"
@@ -60,8 +59,6 @@ Convex = "f65535da-76fb-5f13-bab9-19810c17039a"
 ECOS = "e2685f51-7e38-5353-a97d-a921fd2c8199"
 Makie = "ee78f7c6-11fb-53f2-987a-cfe4a2b5a57a"
 NLsolve = "2774e3e8-f4cf-5e23-947b-6d7e65073b56"
-SparseDiffTools = "47a9eef4-7e08-11e9-0b38-333d64bd3804"
-Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 
 [extensions]
 TrixiCUDAExt = "CUDA"