Increase contrast on Package Info pages

[mbauman]

As reported in https://discourse.julialang.org/t/color-scheme-of-juliahub-package-descriptions/110282/, there are a number of elements with low contrast. The WCAG 2.0 accessibility checker flags the following:

.osano-cm-storage-policy
    <a rel="noopener" tabindex="0" href="https://juliahub.com/company/privacy/" target="_blank" class=" osano-cm-storage-policy osano-cm-content__link osano-cm-link " aria-describedby="osano-cm-aria.newWindow"><!--?lit$30367725$-->Privacy Policy</a>
.custom-placeholder
    <div class="custom-placeholder mb-2 pl-1"> Type <kbd>/</kbd> to search </div>
span[aria-current="location"]
    <span aria-current="location">DifferentialEquations</span>
.col-sm-6.col-lg-3.mb-2:nth-child(2) > .proj-details
    <div class="proj-details">PACKAGE VERSION</div>
.col-sm-6.col-lg-3.mb-2:nth-child(3) > .proj-details
    <div class="proj-details">6.9k MONTHLY DOWNLOADS</div>
.col-6 > .proj-details
    <div class="proj-details">LICENSE</div>
.col-sm-6.col-lg-3.mb-2:nth-child(5) > .proj-details
    <div class="proj-details">HOMEPAGE</div>
.col-lg-3.mb-2.col-12:nth-child(6) > .proj-details
    <div class="proj-details"> CONTRIBUTORS <button type="button" class="btn px-1 py-0 expand-btn btn-link"> show more </button></div>
.col-lg-3.mb-2.col-12:nth-child(7) > .proj-details
    <div class="proj-details"> TOPICS <button type="button" class="btn px-1 py-0 expand-btn btn-link"> show more </button></div>
.col-lg-3.mb-2.col-12:nth-child(8) > .proj-details
    <div class="proj-details">STATUS</div>
.col-auto.col-lg-3.mb-2 > .proj-details
    <div class="proj-details">INSTALLATION</div>