Use a requirement file to install dpctl wheel package (#2413)

The PR proposes to use a requirement file while installing dpctl wheel
package through GitHub actions in `Build docs` and `Coverage` workflows.
This will allow to specified the required dpctl version in one
requirement file.

Author: antonwolfy

Diff for: .github/workflows/build-sphinx.yml

@@ -42,6 +42,7 @@ jobs:
       oneapi-pkgs-env: ''
       # Enable env when it's required to use only conda packages without OneAPI installation
       # oneapi-pkgs-env: '${{ github.workspace }}/environments/oneapi_pkgs.yml'
+      dpctl-pkg-txt: 'environments/dpctl_pkg.txt'
 
     steps:
       - name: Cancel Previous Runs
@@ -149,7 +150,7 @@ jobs:
       - name: Install dpctl
         if: env.oneapi-pkgs-env == ''
         run: |
-          pip install -i https://pypi.anaconda.org/dppy/label/dev/simple dpctl==0.20.0dev0
+          pip install -r ${{ env.dpctl-pkg-txt }}
 
       - name: Conda info
         run: |

Diff for: .github/workflows/generate_coverage.yaml

@@ -26,6 +26,7 @@ jobs:
       oneapi-pkgs-env: ''
       # Enable env when it's required to use only conda packages without OneAPI installation
       # oneapi-pkgs-env: '${{ github.workspace }}/environments/oneapi_pkgs.yml'
+      dpctl-pkg-txt: 'environments/dpctl_pkg.txt'
 
     steps:
       - name: Cancel Previous Runs
@@ -108,7 +109,7 @@ jobs:
       - name: Install dpctl
         if: env.oneapi-pkgs-env == ''
         run: |
-          pip install -i https://pypi.anaconda.org/dppy/label/dev/simple dpctl==0.20.0dev0
+          pip install -r ${{ env.dpctl-pkg-txt }}
 
       - name: Conda info
         run: |

Diff for: environments/dpctl_pkg.txt

@@ -0,0 +1,2 @@
+--index-url https://pypi.anaconda.org/dppy/label/dev/simple
+dpctl>=0.20.0dev0