Trac #34270: .gitpod.yml: Do not hardcode the workspace name as saget…

…rac-mirror

For example https://gitpod.io/#https://github.com/sagemath/sage, which
appears as a link in our manuals, for instance,

- find the link "going to Gitpod" in
https://113a817a9b18c078a108e31522579eab1afac19c--sagemath-
tobias.netlify.app/developer/index.html

does not work because the workspace directory is `/workspace/sage`, not
`/workspace/sagetrac-mirror`

URL: https://trac.sagemath.org/34270
Reported by: mkoeppe
Ticket author(s): Matthias Koeppe
Reviewer(s): Kwankyu Lee

.gitpod.yml

@@ -9,8 +9,8 @@ tasks:
       # Create conda environment
       ./bootstrap-conda
       mamba env create --file src/environment-dev.yml --prefix venv
-      conda config --append envs_dirs /workspace/sagetrac-mirror
-      conda activate /workspace/sagetrac-mirror/venv
+      conda config --append envs_dirs $(pwd)
+      conda activate $(pwd)/venv
       
       # Build sage
       ./bootstrap
@@ -20,8 +20,8 @@ tasks:
 
     command: |
       # Activate conda environment
-      conda config --append envs_dirs /workspace/sagetrac-mirror
-      conda activate /workspace/sagetrac-mirror/venv
+      conda config --append envs_dirs $(pwd)
+      conda activate $(pwd)/venv
 
       # RestructuredText extension recommends python extension, although we have already installed it
       ## So disable the recommendation dialog