nixos/esphome: add state directory to ExecPaths= and ReadWritePaths=

Fixes the following issue:
```
sh: line 1: /var/lib/esphome/.platformio/packages/toolchain-gccarmnoneeabi/bin/arm-none-eabi-g++: Permission denied
```

Signed-off-by: David Wronek <david.wronek@mainlining.org>

nixos/modules/services/home-automation/esphome.nix

@@ -131,6 +131,8 @@ in
         RuntimeDirectory = mkIf cfg.enableUnixSocket "esphome";
         RuntimeDirectoryMode = "0750";
         EnvironmentFile = lib.mkIf (cfg.environmentFile != null) cfg.environmentFile;
+        ExecPaths = "%S/${stateDir}";
+        ReadWritePaths = "%S/${stateDir}";
 
         # Hardening
         CapabilityBoundingSet = "";