dstack [Bug]: vastai gpuhunt returns no offer for fixed disk size

Steps to reproduce

Step 1: Specify fix disk in .dstack.yml eg:

type: dev-environment

# Use either `python` or `image` to configure environment
python: "3.11"

# image: ghcr.io/huggingface/text-generation-inference:latest

ide: vscode

# (Optional) Configure `gpu`, `memory`, `disk`, etc
resources:
  disk: 100GB

Step 2: Do dstack run . -b vastai --gpu 1

Actual behaviour

Output of dstack run

Configuration          .dstack.yml                         
Project                main                                
User                   admin                               
Pool name              default-pool                        
Min resources          2..xCPU, 8GB.., 1xGPU, 100GB (disk) 
Max price              -                                   
Max duration           6h                                  
Spot policy            on-demand                           
Retry policy           no                                  
Creation policy        reuse-or-create                     
Termination policy     destroy-after-idle                  
Termination idle time  300s                                

Continue? [y/n]:

Expected behaviour

Output of dstack run

Configuration          .dstack.yml                           
 Project                main                                  
 User                   admin                                 
 Pool name              default-pool                          
 Min resources          2..xCPU, 8GB.., 1xGPU, 100GB.. (disk) 
 Max price              -                                     
 Max duration           6h                                    
 Spot policy            on-demand                             
 Retry policy           no                                    
 Creation policy        reuse-or-create                       
 Termination policy     destroy-after-idle                    
 Termination idle time  300s                                  

 #  BACKEND  REGION      INSTANCE  RESOURCES                                     SPOT  PRICE      
 1  vastai   us-texas    8115187   32xCPU, 16GB, 1xRTX4090 (24GB), 100GB (disk)  no    $0.50125   
 2  vastai   tw-taiwan   10184745  18xCPU, 8GB, 1xRTX4090 (24GB), 100GB (disk)   no    $0.44861   
 3  vastai   ca-ontario  10593243  6xCPU, 64GB, 1xRTX4090 (24GB), 100GB (disk)   no    $0.41783   
    ...                                                                                           
 Shown 3 of 34 offers, $4.02083 max

Continue? [y/n]:

dstack version

dstack 0.18.0

Server logs

No response

Additional information

Specifying range for storage in .dstack.yml works Eg:

resources:
  disk: 100GB..

or

resources:
  disk: 100GB..200GB