fix: only write version file if supabase directory exists

[sweatybridge]

What kind of change does this PR introduce?

Bug fix

What is the current behavior?

Bash completion is sometimes added to ~/.zshrc files resulting in supabase/.temp/cli-latest created in every directory where a new shell is launched.

What is the new behavior?

Only writes the version file if there's an existing supabase directory.

Additional context

Add any other context or screenshots.

[coveralls]

Pull Request Test Coverage Report for Build 9462591335

Details

• 0 of 1 (0.0%) changed or added relevant line in 1 file are covered.
• 72 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.09%) to 60.016%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
cmd/root.go	0	1	0.0%

Files with Coverage Reduction	New Missed Lines	%
internal/storage/rm/rm.go	2	89.53%
internal/gen/keys/keys.go	5	11.76%
cmd/root.go	65	9.52%

Totals
Change from base Build 9459290596:	-0.09%
Covered Lines:	6870
Relevant Lines:	11447

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 9462680245

Details

• 0 of 1 (0.0%) changed or added relevant line in 1 file are covered.
• 8 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.05%) to 60.052%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
cmd/root.go	0	1	0.0%

Files with Coverage Reduction	New Missed Lines	%
internal/debug/postgres.go	3	64.86%
internal/gen/keys/keys.go	5	11.76%

Totals
Change from base Build 9459290596:	-0.05%
Covered Lines:	6867
Relevant Lines:	11435

---

💛 - Coveralls