I recently installed PostgreSQL 13 on windows 10 and the PostGIS extension via the stack builder. However, when trying to launch the shp2pgsql-gui application to import a shapefile, I get a "libsqlite3-0.dll was not found" error. I can see the file under the bin folder, so I'm not sure where the problem is and googling did not help very much. I wonder what the problem may be because the installation seemed pretty straightforward to have done something wrong.
Copying the "libsqlite3-0.dll" file from \PostgreSQL\13\bin
to PostgreSQL\13\bin\postgisgui
and then running the shp2pgsql-gui application seemed to fix this issue for me.