normalize empty string in dotFormatter to nil #1456

Job	Run time
Smoke test debug adapter (Elixir 1.15.x \| OTP 26.x)	1m 1s
Smoke test language server (Elixir 1.14.x \| OTP 26.x)	3m 0s
Smoke test debug adapter (Elixir 1.14.x \| OTP 26.x)	1m 4s
Smoke test language server (Elixir 1.15.x \| OTP 26.x)	3m 4s
Smoke test debug adapter (Elixir 1.17.x \| OTP 27.x)	24s
Smoke test debug adapter (Elixir 1.18.x \| OTP 27.x)	1m 3s
Smoke test language server (Elixir 1.18.x \| OTP 27.x)	3m 5s
Static analysis	18s
Smoke test debug adapter (Elixir 1.16.x \| OTP 26.x)	1m 5s
Smoke test language server (Elixir 1.17.x \| OTP 27.x)	3m 2s
Smoke test language server (Elixir 1.16.x \| OTP 26.x)	3m 14s
Compatibility test (Elixir ${{ matrix.elixir }} \| OTP ${{ matrix.otp }} \| ${{ matrix.os }})	0s
	20m 20s

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